Fatal Inheritance (7 page)

Truth is what comes from God and not what we ourselves believe is the truth for we are subject to error. Whatever comes to us from God is the truth and our difficulty is to distinguish truth from error, truth from Him and error from ourselves. This is the only task and not distinguishing the wrong from the right, the pain from the joy, the outer from the inner for these are one so long as they come to us from the Source. We have a body and there is the world and we perceive it as the inner and the outer, our skin is the frontier between our sense of Inner and our sense of Outer yet this is an illusion for within us there are elements of the outer and outside of us of the inner. All Truth is outer, all Lies inner. On the Day of Judgement, the Truth will emerge. When man rips the fabric of God’s Truth then only then is he Evil. Before condemning a man for Evil be certain that his thoughts and deeds were not sent to him for a purpose beyond our understanding.

Having told Professor Correns to come and pay us a visit on Wednesday afternoon, I had left the garden gate invitingly open, and upon hearing his step upon the path at three o’clock precisely, I hurried out to greet him. He was looking all about him with an air of great pleasure.

‘The poetry of your garden, Mrs Weatherburn!’ he said admiringly.

I dearly love my garden, which is quite ample compared to others along Malting Lane, stretching up the side of the house to the street as well as behind the house. In spring and summer it is a riot of flowers and sunshine. January, however, is not usually the season at which I most appreciate it. Thanks to the clemency of Cambridge weather it is very green, but the taller plants tend to wilt sadly and have an air of awaiting the spring with the same glum patience I sometimes feel myself when the wintry weeks stretch on for too long. But Professor Correns had already spotted the nearly-empty vegetable patch at the back, in which nothing remained but a few blackened and broken stems.

‘Ah,’ he said, hurrying over eagerly to have a closer look. ‘Yes. I see that you do know peas.’

‘Just the ordinary type,’ I said.

‘Pisum sativum,
’ he said. ‘That is exactly what my own research was concerned with. Having cultivated them, you probably noticed that the peas produced are sometimes green and sometimes a yellow colour; also that they are sometimes round and sometimes wrinkly.’

I had never paid much attention to these details, and dared not mention that the peas that I harvested for the enjoyment of a summer day’s gardening were generally shelled by Mrs Widge. But my conscience was relieved by calling up the image of the dishes of roast mutton that she fondly served us, accompanied by our own garden peas and tiny carrots. Yes, a few were wrinkled and the colour of the peas was not entirely even. Although if any peas looked too yellowish, I suspected that Mrs Widge might actually throw them away. However, I nodded vigorously, and seeing that the professor was on the point of launching into a discourse, I asked him whether he would like to come indoors.

He looked up at the sky, then at the house through the open door of which the wild shouts of the children could be heard, and then suggested that as it was a particularly lovely day for January, we could perhaps take a turn. The idea did not displease me, and hurrying indoors to put on hat and wraps, I called out to the children’s nurse that I was going for a walk and hastened quickly out again before they had time to cling to me with a show of wild protestations performed uniquely for the histrionic fun of it, which tended to redouble in intensity in the presence of outsiders.

‘Let us walk about the Lammas Land,’ I said as we started down the lane. The professor accompanied my steps, looking around him with unmitigated delight.

‘It is like a country village here,’ he said. ‘It is almost difficult to imagine that we are but ten minutes’ walk from the busy colleges.’

‘Less than that, if you count Newnham,’ I said, pointing towards Sidgwick Avenue. ‘It’s just a two-minute walk that way.’ But Professor Correns was not interested in Newnham College. Reaching the end of the lane, we entered Laundress Green, and I began to do the honours of the place, pointing to the public house on the bridge and to the back of the Darwins’ granary with its little white balcony, but he seemed to have something else on his mind. As we crossed over a small bridge under which the river runs sluggishly through the fen grasses, he turned to me with an air of secrecy, and I thought that he was going to pick up the interrupted conversation about the mating habits of pea plants, when instead he said in a hushed tone,

‘Rumour has it that last year you discovered a body floating in this place.’

‘Oh!’ I said. For many months I had been unable to cross the Lammas Land without recalling the events surrounding that murder, but of late that association had begun to fade away under the influence of other more recent events. ‘No, no, rumour exaggerates. I did not find the body, I merely helped in understanding the facts that had led to its being there.’

‘But it was here?’

‘Not quite. It was more over there, I believe. Caught in the reeds and grasses.’

‘I have heard that you are regularly involved in detective activities,’ he went on, and I noted in his tone respect mingled with a curiosity of which he was slightly ashamed but unable to completely repress. The enquiry in his blue eyes was intense and alive with intelligence. Normally I loathe talking about these things, or perceiving the prurient interest they occasionally arouse. But I did not feel that now, and I became aware with a blush that it was because his interest was not directed at the grisly tales of murder, but at myself. This sensation was unusual and, to be quite honest, not unpleasant. In any case, it provoked in me an uncharacteristic expansiveness, and I found myself telling him not only about the girl who had been killed, but, to my own surprise, all about Sebastian and the source of my sudden interest in heredity. And by this circuitous route, having crossed and circled the Lammas Land and Laundress Green from top to bottom, edge to edge and bridge to bridge, we found ourselves naturally back at the subject which had first brought us together, and caused such emotion to Mrs Bates.

‘You were telling me about heredity in peas,’ I said.

‘Of course! Exactly. I was telling you that the stamens of the flower function as the male,’ he responded at once, launching into a lecture with the natural flow of an experienced professor, ‘and the pistil functions as the female organ, which is fertilised by the stamens in the following manner: they shed the yellow powder that you can see upon their tips, the pollen, onto the pistil, and that fertilises it and allows it to produce a pea pod containing peas.

‘Now, if you allow the flower to self-fertilise and obtain a pea pod, from which you extract a pea which you then use as a seed for another pea plant, you will, as I said earlier, obtain a pea plant having characteristics identical to the parent plant; green or yellow, round or wrinkly and so forth. That is because, in this case, the mother and father are from the same plant, so of the same type. Such plants are called purebred, and they carry the strains of their characteristics from generation to generation, exactly as one might see certain characteristics carried down in strains of purebred horses or dogs, for example.

‘What Gregor Mendel wished to do was to see if it was possible to comprehend whether the transmission of visible features in peas and the role of the pollen and the pistil is governed by a discernible theory. To separate the role of pollen and pistil, he cross-fertilised plants of different strains. This is a technique which has been practised by farmers for many, perhaps hundreds, of years: it consists in opening the immature flowers of the pea plant and cutting off the stamens, and then using a small brush or even the fingers to remove pollen from a different plant and brush it onto the immature pistil. One then carefully closes the flower petals and leaves the whole situation alone until the pea pod emerges, after which one can study the properties of the individual peas in the pod, and then plant them and observe the properties of the plants they produce. He was a monk, if you recall, in Brünn, and had all the necessary time and leisure to do as he pleased in the monastery garden, and the approval of his superior as well.

‘In order to carry out numerical observations, Mendel repeated his experiments on many hundreds of plants, crossing the same type with the same type, for each of the many possibilities, again and again, observing and counting the results. What had been believed at first – that crossing a plant with green peas and a plant with yellow peas could produce a plant with either green or yellow peas (regardless of which parent was green and which yellow), and that it was merely a matter of chance – turned out to be false. In fact, crossing purebred strains yielded very clear and observable results. Considering just the property of the peas being green or yellow, he saw over a great number of experiments that crossing two purebred green plants could only produce green plants, and crossing two purebred yellow plants could only produce yellow, whereas crossing a green and a yellow invariably produced a green.

‘He then proceeded to mate purebred plants with those of the second generation of mixings, and now he observed something new. Mating a purebred green with a green that was actually of green and yellow parentage produced only green offspring, but mating a purebred yellow with a green of mixed parentage produced green exactly half the time, and yellow exactly half the time. As for the mating of two mixed plants, the result was a green offspring three-quarters of the time, and a yellow offspring one quarter. Can you guess the rule? It is a purely mathematical question by now!’

I stopped and leant my elbows on the railing of a bridge, ruminating over the pattern he was describing. He stopped next to me, and extracting a crumpled envelope from his pocket together with a stub of pencil, he drew the following diagram.

‘Look!’ he exclaimed. ‘This is Mendel’s stroke of genius, and the picture explains it all! Each organ, whether stamen or pistil, must contain two
markers
of some kind, which can be either green or yellow. From the stamens only one of the two can pass to the offspring, and from the pistils again only one, and these are selected by random chance! In a purebred green plant, both markers will be green for the stamens and the pistils, so, if they are crossed, they can only pass green markers to the offspring, and for purebred yellow it will be the same. But when you cross the plants – then what happens to a plant with one green and one yellow marker?’

‘Well,’ I said, ‘you claimed that crossing a green and a yellow purebred always creates a green, so I am obliged to conclude that a plant with one green and one yellow marker must be green.’

‘Logically spoken!’ he cried and again looked at me with an undue measure of admiration. ‘Mendel called these markers
alleles
, and the fact that green and yellow together make green, he described by saying that the green allele is dominant and the yellow recessive. Thus, of the four possible father-mother combinations green-green, green-yellow, yellow-green and yellow-yellow, only the last one will actually show yellow peas – so only one quarter of the offspring, on average, will be yellow! But the mixed plants will contain alleles that are totally invisible when observing the plants themselves, but that will affect a certain number of the offspring, according to the laws of probability. Generalise this theory to all possible physical traits, and you have the entire theory of their heredity and the manner in which they are passed down through the generations.’

‘Is that mystery not contained in the nature of the alleles?’ I said. ‘They seem to hold the secret of it, whatever they are.’

‘We do not yet know their precise nature,’ he said confidently, ‘but we will. They are some kind of purely physical entity, microscopically small and carried within each living creature. When we have sufficiently powerful microscopes, we will perhaps be able to observe them physically. As to the mechanism that ensures that each creature carries a pair of alleles and passes exactly one of them to the offspring, that is also a physical reality. The power of Mendel’s theory is that it proves that the choice of which allele passes down proceeds according to the laws of probability. For the rest, the only mystery that remains is how God could fabricate machines as utterly complex and fascinating as living creatures surely are. And the question of God’s power will no doubt remain forever beyond our grasp.’

‘You mean that human beings must be content to be satisfied with the physical explanation, as long as it is complete.’

‘For myself,’ he said, ‘between the physical description of the alleles, and the mathematical description of their behaviour, it is the theory that I find the most interesting. Can you imagine that Mendel understood why, when a yellow pea plant is crossed with a purebred green, they will have only green offspring, but exactly one quarter of the grandchildren provided by mating those offspring will be yellow? And how many typical human characteristics of heredity are explained by that same observation?’

‘You’re right – that is striking,’ I said, my thoughts reverting suddenly to Sebastian. ‘I have often heard that many traits are seen to “skip a generation”, and to pass directly from grandparent to grandchild without being visible in the parents. Do you think that Mendel’s theory could really explain it?’

‘But it is certain!’ he said. ‘For one particular example of such a thing, one might say that it could be due to many complex combinations of heredity, but when such a thing is perceived very generally, there is no doubt that it must be interpreted as a consequence of the theory.’

‘This is one of the most fascinating things I have ever heard,’ I declared. I was bemused and seduced by it all: it seemed so very revealing, so daring, so deep and yet so fundamentally simple – and so patently true! ‘But still,’ I went on, ‘there is something I don’t understand. If your theory explains the hereditary transmission of physical features – and I quite understand that human features are subject to a great many more variations than pea plants, and therefore the number of possibilities is gigantic, yet the mathematical laws governing them would be the same – what about the transmission of non-physical attributes?’

‘You mean such as character?’ he asked.

‘Yes. Such as often-noted family tendencies such as a quick temper, or a high intelligence. Or – or musical gifts.’

‘The question is both deep and subtle,’ he said, ‘and I have pondered it myself a great deal. I have finally arrived at the conclusion that, in spite of appearances, there is no way to be certain that these traits are not just as much consequences of a physical disposition as visible features are. Could not a musical talent be a consequence of a physical superiority of the ears, causing more acute appreciation of sounds that already seem beautiful to everyone?’