SIGNIFICANCE OF NUCLEOLI 



199 



identical in character with the plasmosomes or nucleoli seen 

 within the nuclear membrane, and have observed that as they 

 pass to a farther distance from the nucleus they enlarge into 

 definite secretory granules. It is with the exact stages of this 

 process that there has been and still is some debate : whether 

 they project as buds from the nuclear membrane or make their 

 way out from pores opening into the same ; whether they finally 

 dissolve within the cell or undergo solution when discharged into 

 the external medium. But Professors Macallum, Carlier, and 

 Bensley are all here, and I must not further steal their fire. I 

 would only add that what has been determined in the animal 



Fig. 14. — Cells of the salivary gland (after Maximow) to show (a) development of 

 the plasmosomes within the nucleus, (b) passage of these out of the nucleus into 

 the surrounding cell substance, with subsequent conversion of the same into 

 granules or globules. Cell 3 is abnormal, showing exhaustion of nuclear material. 

 In the cell are globules of various sizes, some still taking on the nuclear stain, 

 others taking on a contrast stain, while others (c) show a centre taking on the 

 stain of nuclear chromatin, with outer zone staining the same as the cell secretion. 



cells holds for the plant cell also. Thus Torrey has described 

 a succession of changes in connexion with the nucleus and cell 

 body in the germinating maize seed associated with the production 

 of diastase. The processes are of an identical nature : deep- 

 staining granules are first seen in the nuclei, whence these exude 

 in small streams into the cytoplasm ; scattered at first through 

 the cell, these later become collected at that end next to the 

 endosperm, where they become ultimately dissolved. It is follow- 

 ing upon their dissociation that the first action of a ferment upon 

 the cell wall and matrix of the endosperm becomes evident. 



Nor is it only in connexion with secretions possessing ferment 

 action that we have evidence of nuclear function. In plants 

 Schniewind Thies has observed nuclear changes in the nectar 



