432 TorRREY: CYTOLOGICAL CHANGES 
tongue there is a clear protoplasmic zone and a granular zone; a 
serous glandular cell is filled with granules during the resting 
period; a like phenomenon is seen in the pepsin-secreting cells. 
According to Ward,* during the secretion of rhamnase by Kham- 
nus infectorius granules appear. 
In animal tissues the secretions are, as a rule, intermittent, but 
in plant tissues, according to Green, they are prolonged and prob- 
ably only to a slight degree intermittent. This he explains by the 
fact that, in the animal, digestion is continually repeated, whereas 
in plants the utilization of reserve materials is a continuous and 
very gradual process. During the first three or four days, how- 
ever, in the case of maize and probably all the Gramineae there is 
clearly an intermittence in the secretion of the enzyme. 
The active part taken by the nucleus in secretion in plants, at 
least, is in complete harmony with the view that it is the metabolic 
center of the cell. Verworn, in his General Physiology, cites a 
number of instances in which the nucleus takes an active part in 
the nutrition and growth of the cell. Although, as he observes, 
the presence of a membrane generally necessitates the exchange 
of liquids between nucleus and protoplasm, yet many observers, 
among them Fromman and Auerbach, “have observed on the 
part of the nucleus a direct ingestion and extrusion of granules 
and flakes.” The ejection of granules from the nucleus of the 
diastase-secreting cell is another case to the point. 
A general review of the literature on secretion in plants and 
animals leads one to the conclusion that in the two cases we have 
a different state of affairs. In both the nucleus is the ultimate 
source of the secretory product but in plants it is far more directly 
concerned than in animals ; in the one it is active and in the other 
passive. 
GENERAL CONCLUSIONS 
_ 1. In the Gramineae “diastase of secretion . 
nucleus of the epidermal cells of the scutellum. For: _ oe 
(a) At the beginning of germination the nuclei contain dar 7 
staining granules, but there are few or none in the cytoplasm. E 
(4) At this same stage, through very small breaks in he a 
branes of the heavily loaded nuclei, granules are beginning ~ 
exude in small streams. a 
” arises in the 
* Green, R., Soluble Ferments and Fermentation, 379-. 
