Although the new evolution differs from the old in the points mentioned above, the two theories obviously agree very closely in the nature of their arguments and conclusions. When, to satisfy our craving for causality, biologists transform the visible complexity of the adult organism into a latent complexity of the germ, and try to express this by imaginary tokens, by minute and complicated particles cohering into a system, they are making a phantasmal image which, indeed, apparently may satisfy the craving for causality (to satisfy which it was invented), but which eludes the control of concrete thought, by dealing with a complexity that is latent, and perhaps only imaginary. Thus, craftily, they prepare for our craving after causality a slumbrous pillow, in the manner of the philosophers who would refer the creation of the world to a supernatural principle. But their pillow of sleep is dangerous for biological research; he who builds such castles in the air easily mistakes his imaginary bricks, invented to explain the complexity, for real stones. He entangles himself in the cobwebs of his own thoughts, which seem to him so logical, that finally he trusts the labour of his mind more than Nature herself. 'Experiment,' says Weismann in _The Germplasm_, 'is not the only way to reach general views, nor is it always the safest means of discrimination, although at first it seems conclusive....[3] It seems to me that in this case we can draw more prudent conclusions from the general facts of inheritance than from the results of experiments that are neither quite clear nor undubious, although in themselves they are most valuable, and deserve the most careful consideration. If one remembers what was said in my section on the architecture of the germplasm as the basis of the theory of determinants, it will be agreed with me that ontogeny must find its explanation in evolution, and not in epigenesis.'[4] I take up a more epigenetic position, and years ago I attacked evolutionary doctrines in many of their modifications.[5] Thus, in the _Studien zur Blätter Theorie_, published by Richard Hertwig and myself, I combated the supposed law that the germinal layers histologically were primitive organs. Next, in a pamphlet entitled _The Problem of Fertilisation: a Theory of Heredity_, I attempted to disprove the principle of His that there were organ-building foci in the germ. In my treatise _On Ovogenesis and Spermatogenesis in the Nematodes_, I declared against the suppositions involved in Weismann's doctrine of the germplasm, and sharply distinguished the theory, simultaneously propounded by Strasburger and myself, that the nucleus is the bearer of the hereditary material, from the evolutionistic interpretation given it by Weismann.