ON THE MATURE OF CELL-ORGANIZATIOX. 95 



tiation of nuclear substance. The developmental history of 

 these two substances naturally leads us to regard them as 

 independent structures, although each is necessary to the 

 physiological existence of the other. They are not, therefore, 

 morphological organs of the cell in the sense of the term as 

 we have explained it. Furthermore, the phenomena of division 

 in the nucleus and cytoplasm remind us forcibly of the mode 

 of origin of the soredia in the lichen ; nor is this remarkable, if 

 a nucleated cell is, like the lichen, a symbiotic community of 

 two dissimilar organisms. The single soredium is a miniature 

 lichen, consisting of one or more algal cells with a weft of 

 fungal tissue around them. The algal and fungal elements in 

 a single soredium are derived from the corresponding elements 

 in the mother lichen-thallus, just as the daughter cell derives 

 its nucleus and cytoplasm from the corresponding elements in 

 the mother cell. 



The most convincing argument proving the symbiotic 

 character of a lichen consists in the synthetic production of 

 certain species of lichens, by bringing algal and fungal 

 elements together. If, therefore, the morphological rela- 

 tionship between nucleus and cytoplasm in a ceil is that of 

 a symbiotic community, the fact analogous to the artificial 

 synthesis of lichens must be found in the cell. I venture to 

 suggest that such a synthesis of a living cell has been accom- 

 plished. I refer to Verworn's l experiment on the Radiolarian, 

 TJialassicolla. Verworn took three vessels of equal size, and 

 in the first he put a number of normal TJialassicolla ; in the 

 second, he put one which had its central capsule with its 

 nucleus removed ; in the third, he placed an individual whose 

 central capsule had been removed and replaced by the trans- 

 plantation of the central capsule of another individual of the 

 same species. The Radiolarian in the third vessel was, 

 therefore, a synthetic one, the extra capsular protoplasm lying 

 outside of the central capsule, being derived from one indi- 

 vidual, and the central capsule itself, with its nucleus, being 

 derived from another. In the course of time, the TJialassi- 

 colla which had lost its nucleus by the removal of its central 



1 Verworn, loc. cit., p. 42. 



