MODERNBIOLOGY 5 67 



once won Weismann's keen approval, but it met with opposition from other 

 quarters; as, for instance, from O. Hertwig, who held that upon the first 

 division of the egg it should be possible to see something of this struggle 

 between the cells, but that, on the contrary, the first easily observable em- 

 bryonic cells show no inclination whatever for mutual strife, but rather 

 each one has its carefully defined form and place. Weismann, however, 

 adopted the idea of natural selection within the organism and combined it 

 with his germinal-plasm theory. In a work entitled Uber Germinalselektion 

 he declares that between the various parts of the body and their "deter- 

 minants" in the germinal plasm there exists reciprocal action; if, now, 

 an organ is not used, its determinants are weakened and annihilated by 

 the struggle within the organism, and the organ disappears in succeeding 

 generations; in this way, for instance, the posterior extremities of the whale 

 have been lost. But, all the same, Weismann comes in this way, although 

 indirectly, to accept the inheritance of acquired characters, which indicates 

 that the theory of selection finds it difficult to do without this auxiliary 

 hypothesis. We shall here leave the omnipotence of natural selection and 

 pass on to its diametrical opposite, neo-Lamarckism. 



Lamarck's theory of the direct influence of habits of life upon the bodily 

 structure of the individual and its offspring gained strong support towards 

 the close of the century, especially in France. When the supporters of Cuvier 

 finally left the arena, it was to Lamarck that people turned for a basis for 

 their biological ideas. When the belief in the constancy of species had to 

 give way to the theory of evolution, the form that this was to take was 

 readily sought from a fellow-countryman, and, moreover, an older man than 

 Darwin; thus "transformism," as it was here called, could also claim to be 

 an originally French science. Lamarck's theory found an eloquent supporter 

 in Alfred Giard. Born in 1846, he studied at the Ecole Normale in Paris 

 and eventually became professor of zoology at the Sorbonne and head of the 

 marine laboratory at Wimereux, near Boulogne; he held that post with suc- 

 cess until his death, in 1908, being especially known for his profound studies 

 of a number of marine animal forms. Under the characteristic title Contro- 

 verses transjormistes he collected some years before his death a series of con- 

 tributions to the problem of descent, in which he examined and further 

 developed Lamarck's doctrines. According to Giard, evolution proceeds un- 

 der the influence of two categories of factors; namely, the primary, which 

 directly influence the individual and indirectly its offspring, and among 

 which are mentioned light, temperature, food, and relations to other beings 

 — that is to say, the struggle for existence — and the secondary, which 

 include everything that is adapted to remove less suitable forms of life — 

 that is to say, natural selection. Giard now takes upon himself to prove the 

 existence of the primary factors, and he adduces quite a number of proofs. 



