222 DARWINISM TO-DAY. 



of inactivity, in reserve, in order to be transmitted to the daughter 

 nucleus when the cell divides. They can divide themselves, and it 

 is indeed necessary that this be so in order that the two daughter 

 nuclei can each receive a complete lot of the representative pan- 

 genes; but they do not manifest in the nucleus their special proper- 

 ties, which remain in a latent state. There is no exception to this 

 except in the case of those certain pangenes which control the 

 division of the nucleus. These enter into activity at the necessary 

 moment in order to determine the characters of the division and 

 in particular the position of the plane of segmentation. 



The cytoplasm is also composed of pangenes ; but these pangenes,. 

 with the exception of those which come from the cytoplasm of the 

 egg. come from the nucleus. From the nucleus there come, in fact, 

 pangenes which distribute themselves in the cytoplasm and multiply 

 there abundantly. These pangenes are exclusively those of which 

 the cytoplasm has need in order to manifest characters and proper- 

 ties which belong to the cell, and it is by delivering to it such and 

 such pangenes and no others that the nucleus rules the cytoplasm, 

 which would remain inert were it not for this infusion of living 

 and active particles. 



There is, then, a great difference between the nucleus and the 

 cytoplasm from the point of view of the pangenetic constitution. 

 Each nucleus contains in general all the pangenes of the individual 

 united undoubtedly into groups more or less considerable, which lie 

 in the chromatic filaments, and these groups, analogous to the 

 gemmules of Darwin's theory, probably form those little grains 

 arranged in rows, which are revealed under a great microscopic 

 magnification of the chromatic threads. But there are one, two, or, 

 at most, a small number of pangenes of each kind; all are inactive 

 save at the moment of division, those which rule this phenomenon; 

 they can multiply themselves but slightly, and in general they do 

 not divide except to replace those which emigrate into the cyto- 

 plasm and to furnish at the moment of division to each daughter 

 nucleus the complete lot which it ought to receive. In the cyto- 

 plasm, on the contrary, there is but a small number of kinds of 

 pangenes immigrated from the nucleus in the quantity exactly 

 necessary, but there these pangenes are enormously multiplying, so 

 that there is a very great number of each kind, and they are almost 

 always in a state of activity. 



B. Hatschek has recently proposed ("Hypothese der Organischen 



Vererbung," 1905) a new micromeric theory which postulates that 



Eatschek's the protoplasm is composed of two different kinds of 



theory. biomolecules ; one called ergatules, which function as- 



similatively, that is, take up food-stuff and excrete waste, but do not 



