374 journal of Comparative Neurology and Psychology. 



to type so that the mosaic tendency cannot be indefinitely extended, 

 and the regulative process shows that a total equilibrium of the 

 more or less analytically distributed forces still exist. 



It is inevitable that in considering any application of dynamics 

 to development w^e should inquire into its bearing upon Weis- 

 mann's postulates of the continuity and invariability of the germ- 

 plasm. It will be remembered that, according to Weismann, the 

 overplus of germ-plasm not used in individual development is 

 handed over to the custody of the new individual and, in this con- 

 dition, is capable of growth and multiplication at the expense of 

 nutrient materials supplied by the somatoplasm, and while thus 

 growing it retains its original highly complex structure. This 

 process continues from individual to individual without change as, 

 to use Romanes' illustration, yeast might be transplanted from 

 vat to vat, the successive vats representing successive generations 

 of progeny. 



Now it is plain that certain types of activity are inoperative on 

 other types. Some vibrations will pass through others unchanged. 

 Some bodies are relatively opaque to one set of vibrations but 

 transparent to other kinds or phases of vibration. It is not in- 

 herently impossible that the trajectory corresponding to any given 

 germplasm should be transparent to the specific vibrations of its 

 somatoplasm, yet the fact that the germplasm is housed in a 

 medium of activities in which the total activity of the organism 

 is in some sort continually reflected makes it inherently improbable 

 that there should be absolute insulation. Inasmuch as Weismann 

 was forced finally to abandon his distinction between germ cells and 

 somatic cells by suggesting that only the nucleoplasm of the former 

 are bearers of the invariable material of heredity and thus the 

 nucleus became the center of interest, it is interesting to observe 

 that non-nuclear parts of the germ cell are found to be capable of 

 multiplication though it might, of course, be suggested in such 

 cases that nuclear materials or forces are diff^used t! roughout the 

 cytoplasm. "Enucleated fragments of fertilized eggs (in Denta- 

 lium) pass through alternating stages of activity and quiescence 

 corresponding with the division rhythm of the nucleated half, and 

 form the polar lobes as if still forming a part of a complete embryo."^ 



In answering Dr. Vines' criticismof his theory of the immortality 

 of micro-organisms and the germ plasm, Weismann oflPered a 



^Wilson. Experimental Studies in Germal Localization, p. 69. 



