Now I had a considerable number of rabbit embryos preserved in alcohol, and though it was not very accurate to weigh them as alcoholic specimens, in order to determine their true weight, yet I resolved to do so as it was the best means at my disposal at the time. The result of that weighing was very interesting to me, because it showed that in the period of nine to fifteen days the rabbit had, on an average, added 704 per cent, to their weight daily; but in the period of from fifteen to twenty days, the addition is very much less than this, only 212 per cent. But these rabbits at ten days have already had a considerable period of development behind them, and as we have discovered that the younger the annual the more rapid its growth, we are safe, it seems to me—since we have learned that from the tenth to the fifteenth day there is a daily increase of over 700 per cent.—in assuming that in yet younger rabbits an increase of a thousand per cent, per day actually occurs. That is not so extraordinary an assumption, for bacteria are known to divide every half hour, and if the little bacterium divides and grows up to full size in half an hour, and then divides again, it means that within a half hour one bacterium has become two, and has increased, obviously, 100 per cent.; and if those two again divide as before, we should have four bacteria at the end of an hour—an increase of 400 per cent., and at the end of another half hour, of 800 per cent., and so on ever in geometrical progression. We learn, then, that bacteria may in a few hours add 1,000 per cent, to their original weight, and it is not by any means an exorbitant demand upon our credulity to accept the conclusion that in their early stages, rabbits and other mammals and birds are capable of growing at least 1,000 per cent, a day. If this be true, and it doubtless is true, we can adopt it as a convenient basis for comparison. As we learned from the rate curves, which were projected upon the screen earlier during the hour, the male rabbit gains in one day immediately after birth nearly eighteen per cent.—seventeen and four tenths per cent.—and the female rabbit gains nearly seventeen per cent. Now we can estimate the loss very simply by deducting this rate, which is the capacity of the animal to grow persisting at birth, from its original capacity, which we assume to have been 1,000 per cent, per day. And if we do that the result is obvious. Over 98 per cent, of the original growth power of the rabbit or of the chick has been lost at the time of birth or hatching, respectively, and the same thing is equally true of man. We start out at birth certainly with less than two per cent, of the original growth power with which we were endowed. Over 98 per cent, of the loss is accomplished before birth—less than two per cent, after birth. That, I think is a rather unexpected conclusion, certainly not one which, until I began to study the subject more carefully, I in the least expected; and even now when I have become more familiar with it, it still fills me with astonishment, it is so different from the conception of the process of development as we commonly hold it, from our conclusions based on our acquaintance
