192 THE CONTINUITY OF THE GEEM-PLASM AS THE 



successive detachment of divisions, brigades, regiments, battalions, 

 companies, etc. ; and as the groups become simpler so does their 

 sphere of action become limited. It must be admitted that this 

 metaphor is imperfect in two respects, first, because the quantity 

 of the nucleoplasm is not diminished, but only its complexity, and 

 secondly, because the strength of an army chiefly depends upon its 

 numbers, not on the complexity of its constitution. And we must 

 also guard against the supposition that unequal nuclear division 

 simply means a separation of part of the molecular structure, 

 like the detachment of a regiment from a brigade. On the con- 

 trary, the molecular constitution of the mother-nucleus is certainly 

 changed during division in such a way that one or both halves 

 receive a new structure which did not exist before their forma- 

 tion. 



My opinion as to the behaviour of the idioplasm during 

 ontogeny, not only differs from that of Nageli, in that the latter 

 maintains that the idioplasm only undergoes changes in its ' con- 

 ditions of tension and movement,' but also because he imagines 

 this substance to be composed of the preformed germs of structures 

 (' Anlagen '). Nageli's views are obviously bound up with his 

 theory of a continuous network of idioplasm throughout the whole 

 body; perhaps he would have adopted other conclusions had he 

 been aware of the fact that the idioplasm must only be sought for 

 in the nuclei. Niigeli's views as to ontogeny can be best seen in 

 the following passages : ' As soon as ontogenetic development 

 begins, the groups of micellae in the idioplasm which effect the first 

 stage of development, enter upon active growth : such activity 

 causes a passive growth 'of the other groups, and an increase in 

 the whole idioplasm, perhaps to many times its former bulk. But 

 the intensities of growth in the two series of groups are unequal, 

 and consequently an increasing tension is produced which sooner 

 or later, according to the number, arrangement, and energy of the 

 active groups, necessarily renders the continuation of the process 

 impossible. In consequence of such disturbance to the equilibrium, 

 active growth now takes place in the next group, leading to fresh 

 irritation, and this group then reacts more strongly than all the 

 others upon the tension which first stimulated its activity. These 

 changes are repeated until all the groups are gone through, and 

 the ontogenetic development finally reaches the stage at which 



