Basil C. H. Harvey 217 
suggestion is afforded that somewhat similar mechanical influences, 
naturally produced, may account for the ontogenetic production of this 
special form of mucosa. Quite in accord with this suggestion is that 
offered by Bensley, 02, as explanation of the differentiation of the cardiac 
mucous membrane. He thinks it may be effected by the action of me- 
chanical forces naturally produced, operating through many successive 
generations and associated with natural selection. 
Cade’s work, while extremely important and significant, seemed to 
leave unanswered several questions which naturally arise in connection 
with it. First: Are these changes which he observed constant and 
permanent? He observed them in a single dog and a single cat, and at 
only one stage after operation, namely, that of six and a half months. 
He believed they were permanent, but lamented the lack of material in 
which to study later stages. He was quite sure, however, that at such 
stages the changes would be yet more marked than in those which he 
studied. Second: What becomes of the parietal cells which have dis- 
appeared? Do they become disintegrated or transformed into other 
cells? No suggestion of an answer to these questions was offered. 
Third: What becomes of the ferment cells which disappear? Are they 
disintegrated or transformed? He thought they were transformed into 
the mucous cells which replaced them, but no evidence beyond the fact 
of replacement is adduced. Fourth: Whence come the new mucous 
cells which occupy their places? He believed they arose by transforma- 
tion of the ferment cells, but an equally legitimate conclusion, as far 
as his experiment could explain the question, would be that they arose 
by the division of previously existing mucous cells found constantly, 
though in small numbers, in the gland bodies. It is true that evidences 
of division in these cells are reported as being exceedingly rare by Biz- 
zozero, 93, and that none were actually found in Cade’s preparations, 
but it seems quite possible that the stimulus of the operation and of 
the altered conditions produced by the operation might perhaps have 
caused their production in extraordinary numbers soon after it took 
place and before six and a half months had elapsed there might have 
arisen in this way a sufficient number of new cells to form a complete 
epithelial lining for the gland bodies and the process may thereupon 
have ceased. It is also possible that the mucous cells of similar character 
in the neck region, which are seen frequently undergoing mitotic division, 
might have produced many new cells which moved down into the gland 
bodies and replaced the ferment cells which were disappearing. His 
assumption that the new mucous cells arise by transformation of zymo- 
