AS THE ELEMENTAL GERM OF AN ORGANISM 349 



derived from the ovum, contain equal quantities of the hereditary 

 mass. Hence this must grow and multiply in the cell before 

 division takes place. All idioblasts must divide and must be 

 transmitted to the daughter-cells, in equal proportions both as 

 regards quality and quantity. 



Nageli (IX. 20, p. 531) has enunciated the same view : " Idio- 

 plasm, by continuously and proportionately increasing, splits itself 

 up during cell-division by means of which the organism grows 

 into as many parts as there are individual cells." Therefore, 

 " each cell of the organism is capable, as far as the idioplasm is 

 concerned, of becoming the germ of a new individual. Whether 

 this potentiality ever becomes a reality, depends upon the nature 

 of the nutrient plasm (somatoplasm)." 



If we look upon the vital processes of the cells from this second 

 point of view, there can be no doubt that the nuclear substance is 

 the only one amongst all the constituents of the cell, which is able 

 to fulfil all the conditions in every respect. 



The nucleus is strikingly uniform in all plant and animal 

 elementary tissues. If we disregard a few exceptions, which 

 require a separate explanation, the nuclei of all the elementary 

 tissues of the same organism resemble each other closelv, as 

 regards shape and size, whilst the protoplasm differs in quantity 

 to a marked degree. In an endothelium cell, or in a portion of 

 muscle or tendon, the nucleus has almost the same characters and 

 contains the same substances as an epidermal, liver, or cartilage 

 cell, whilst, in the former case, the protoplasm is barely distin- 

 guishable, and, in the latter, is present in large quantities. 



The striking and complicated phenomena of the process of 

 nuclear division, are both more important and more comprehensi- 

 ble, when regarded in the light of our theory. The arrangement 

 of the substance into fibrilla?, which consist of small microsomes, 

 arranged alongside of each other, the formation of loops and 

 spindles, the longitudinal halving of the fibrils, and the mode of 

 their distribution amongst the daughter-nuclei, can only serve one 

 purpose, namely, to halve the nuclear substance and to apportion 

 it equally amongst the daughter-cells. 



Roux, from another stand-point, has already pertinently de- 

 nominated " the nuclear division-figures as mechanisms, by means 

 of which it is possible to divide the nucleus, not only accord- 

 ing to its own volume, but according to the volume and nature 

 of its special constituents. The essential part of the process 



