286 NATURAL SCIENCE. Oct., 



theory that the presence or absence of the germ-cells in an individual 

 should affect the ontogeny of the soma. He assumes that the 

 determinants for the soma are separated off and determine a certain 

 ontogeny, which is not affected by the fate of the determinants of 

 succeeding generations contained in the germ-cells and germ-tracks ; 

 and yet we know that male secondary sexual characters are not 

 developed if the young male is castrated. The development of these 

 characters depends on the normal presence of the testes and their 

 germ-cells in the individual. Weismann -mentions this fact, but how 

 does he connect it with his theory ? He simply concludes that in 

 such cases the secondary sexual characters of both sexes are present 

 in each individual, and one or the other set develop according to 

 circumstances. He makes no attempt to show why the particular 

 circumstance which determines the development is the presence or 

 removal of the generative organs. The fact of the course of ontogeny 

 in this case being affected in so radical a manner by the mere 

 presence of the generative organs, is alone sufficient to overthrow 

 his fundamental assumption of the essential independence of the 

 soma and the germ-cells contained within it. 



Degeneration of organs is a phenomenon in which recapitulation 

 is particularly well exhibited. Scarcely any case is known of an organ 

 which has disappeared or become rudimentary in the adult condition, 

 and which is not more perfectly developed or developed to some extent 

 in earlier stages of the life-history. Even the limbs of snakes are 

 indicated to some extent in the embryo, and the teeth of the right 

 whale are present in the foetus ; but the loss of the eyes in blind 

 subterranean animals is the instance I prefer to bring forward here. 

 On the Natural Selection theory it is no advantage to such animals 

 that the larvae or the young should have eyes better developed than 

 the adults. Yet this is known to be the case in the blind amphibian 

 Proteus of the caves of Dalmatia, the blind crayfish of the 

 caves of Kentucky, and in other cases. This case has a 

 superiority over others in my argument, because there^is no change 

 of conditions as in the frog and the flat-fish : the whole development 

 takes place in the dark. Weismann considers this case in relation to 

 his theory, but does not succeed in showing any logical connection 

 between his assumptions and the phenomenon. He supposes that 

 the determinants for the degenerating organ first begin to lose their 

 power of multiplication, and then a continually increasing number 

 disappear. This means, presumably, that a succession of determinants 

 is necessary to supply the successive generations of cells which keep 

 an organ in proper condition, and that the reserve determinants in the 

 soma are continually multiplying when degeneration does not take 

 place ; but we know that in the life of the individual this " multipli- 

 cation of determinants " is checked or stopped by disuse, and we do 

 not know how the "power of multiplication" is diminished in the 

 germ-plasm. In spite of all that has been discovered or conceived up 



