44 THE BIOLOGICAL PROBLEM OF TO-DAY 



dividual of a higher rank ; these cells resemble one 

 another so completely in appearance and in qualities 

 that there can be as little doubt as in the case of 

 unicellular organisms that they arose by doubling 

 division. 



It is certain, then, that there exist multicellular 

 bodies, often consisting of many thousand cells, in 

 which each part retains the qualities of the egg 

 from which it arose by doubling division, and 

 which, as that method implies, possess the rudi- 

 ments of the whole of which each is a part. 



In this category there naturally fall the multi- 

 nucleated masses of protoplasm, sometimes highly 

 organised, in which every nucleus, surrounded by 

 a shell of protoplasm, is capable of reproducing the 

 whole. I am thinking of the slime-fungi (Myxo- 

 mycetes), with their peculiar formation of repro- 

 ductive bodies ; of the ' acellular plants,' which in 

 some cases closely resemble multicellular species in 

 their formation of leaf and root, and in their mode 

 of growth, as, for instance, Caulerpa, the multi- 

 nucleated Foraminifera and Radiolarians. For, ac- 

 cording to our definition of the cell, a multinucleated 

 organism potentially is a multicellular organism. 



In this matter Weismann has assumed a position 

 which leads to peculiar consequences. In his 

 opinion, somatic cells and germ-cells were sharply 

 distinct at their first appearance in evolution, and 

 have remained so ever since. Transitional forms 

 between them are nowhere to be found. It would 

 be inconsistent with his theory of the germplasm 

 had somatic cells contained germplasm as their 



