J 



6 An Examination of Weismannism. 



mission previously referred to, whereby idio-plasm-B 

 of one stage becomes successively transformed into 

 the idio- plasms -A of successive stages. In the 

 former case, at whatever stage of ontogeny the 

 transmission may start from, the idio-plasm-B from 

 that stage lies dormant, and is never destined to 

 undergo further differentiation, unless the results of 

 accident or disease should call upon it to do so. In 

 the latter case, on the other hand, the idio-plasm-B 

 of any given stage is passed on to the next stage 

 for the express purpose of transforming itself into 

 the idio -plasms -A of that and, in due order, of all 

 subsequent stages. 



It will be observed that all this elaboration of the 

 original theory of germ-plasm — an elaboration which 

 is largely derived from the speculative writings of 

 Nageli — serves no other purpose than that of indicating 

 what Professor Weismann now regards as the most 

 probable mode in which germ-plasm undergoes its 

 modification into the various kinds of somatic-cells. 

 For, inasmuch as the idio-plasms-B of all somatic-cells 

 are originally derived from that of the germ-cell, and 

 inasmuch as each expends its formative energies 

 exclusively in constructing and controlling the cells 

 which, as idio-plasms-A, they respectively inhabit, it 

 is still the germ-plasm of the original germ-cell that 

 is finally converted into the various tissues which 

 together constitute the soma — notwithstanding that, 

 in order thus to become transmuted into body-sub- 

 stance, or somato-plasm, it must pass through the sundry 

 intermediate stages of idio-plasm-B, idio-plasm-A, and 

 cytoplasm, of any given ontogenetic stage. Hence 



