WEISMANN'S THEORY OF THE GERMPLASM 33 



A mass of protoplasm with several nuclei (like 

 the myxomycetes, cceloblasts, etc.) has the morpho- 

 logical value of a number of cells (synergides), 

 corresponding to the number of the nuclei. 



The means by which the continuity of life is 

 maintained is the capacity of the cell to manifold 

 itself by division, so forming two or more separate 

 pieces. The process, which in most cases is asso- 

 ciated with complicated changes of the nuclear 

 contents, appears essentially to consist of the 

 following : The elementary units of the cell (centro- 

 somes, chromatin bodies in the case of nuclear 

 division), being endowed with special energy re- 

 sulting from the processes of growth, divide, and 

 the elementary products of division separate into 

 two groups, which move from the middle line ; 



ductive cells contains the hereditary mass or germinal material. 

 My reasons may be found in my text-book on TJie Cell (English 

 edit., p. 274). Briefly they are: 1. The equivalence of the male 

 and female hereditary masses. 2. The equal distribution of the 

 growing nuclear mass of the primary egg-cell among the daughter- 

 cells that, arising from it, build up the organism. 3. The preserva- 

 tion of a constancy of bulk of the hereditary mass when fertilization 

 occurs. 4. The isotropism of protoplasm. Following Pfliiger, I 

 mean by isotropism that the protoplasm of the egg does not contain 

 local areas for the formation of different organs ; but that, according 

 to the conditions, any part of the protoplasm may be employed in 

 the formation of any organ. Isotropism is merely the negation of 

 His' doctrine of the presence of local areas for definite organs, and 

 without losing its meaning, is compatible with the fact that many 

 eggs have their poles different, and that others have a bilateral 

 symmetry which determines the plane of the first division. 5. The 

 fact that the first stages of many embryonic developments consist 

 in the multiplication of the nuclear material and its distribution 

 in the yolk, following which the yolk-mass cleaves into cells. 



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