PHYSIOLOGY OF PEPSIN-FORMING GLANDS. 
707 
show a networked appearance, from the presence of a lightly-stained protoplasmic with 
a darker interprotoplasmic portion. When the cells are similarly treated after a period 
of secretion the networked appearance disappears from the outer portion of the cells ; 
it now is homogeneous—the protoplasm stains deeper than before. After prolonged 
secretion the cells stain equal and fairly darkly throughout. 
In all these glands, however, the increase of substance in the cell-protoplasm 
capable of staining with osmic acid, although distinct, is not so marked as it is in the 
gastric glands. 
Grutzner" has independently come to a somewhat similar conclusion. He found in 
all the salivary and gastric glands investigated by him a difference of tint in osmic 
acid specimens of the resting and of the active glands. The former he found to be 
grey-green, the latter a dirty ( schmutzig ) brown. This, indeed, represents not unfairly 
the general difference in tint of the glands in the respective states when examined 
with not too high a power. I should prefer to call the tint of the one yellowdirown 
and that of the other brown-black. Grutzner applied his description to the cells as 
a whole; the yellow-brown tint is, however, in the main due to the staining of the cell- 
granules, the brown-black tint in the main to the staining of the cell-protoplasm. 
It will be noticed that my views on the processes taking place during secretion are 
opposed to the lately-advanced views of Stricker and Spina, and on the whole similar 
to those of Heidenhain. The theory of Stricker and Spina! is based upon some 
interesting facts observed by them in the glands of the web and nictitating membrane 
of the Frog. The theory so deduced holds, they think, for all secretory glands ; they 
attempt to show that it holds for the salivary glands. 
I may be pardoned for not entering into a discussion of the question as long as the 
objections raised by ITeidenhainJ remain unanswered. I will only remark that in my 
observations on serous and mucous salivary glands, on gastric and pancreatic glands, 
and on the liver, I have seen nothing in favour of the theory of Stricker and Spina, 
but many things against it. 
The observations, an account of which has been given in this paper, were made in 
the Physiological Laboratory of the University of Cambridge. I cannot too much 
thank Dr. Foster for the kindness and generosity with which he has placed at my 
disposal all the material and apparatus belonging to him. 
* Grutzner, Pfluger’s Arch., Bd. xx., s. 399, 1879. 
t Stricker and Spina, Sitzb. d. k. Akad der Wissensch. z. Jena, Bd. Ixxx., abt. iii., 1879. 
X Heidenhain, Hermann’s ‘ Hdb. d. Physiol.,’ Bd. v.., Th. i., s. 414, 1880. 
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