124 Chittenden and Cummins—Influence of various Substances, ete. 
in the action of sodium tetraborate on the salivary ferment and on 
trypsin. 
It is moreover, evident, from a comparison of the results obtained 
with the three ferments, that under the conditions of dilution, ete., 
with which our experiments were tried, the salivary ferment is the 
most sensitive to the action of the various salts, while of the other 
two, trypsin is as a rule most readily affected. Still, it is hardly 
possible to draw a direct comparison between the two proteolytic 
ferments, since they act under such different conditions; the fact 
that pepsin acts only in an acid medium and that both the strength 
and nature of the acid affect the activity of the ferment, intro- 
duces an additional factor which makes direct comparison in the 
case of the two ferments impossible. The possible reason for the 
slight acceleration of proteolytic action produced by several neutral 
salts, in the case of pepsin-hydrochloric acid, has been already referred 
to; but why neutral salts, which in large percentages show retarding 
action, should in smaller percentages added to a neutral solution of 
the ferment (ptyalin or trypsin) produce acceleration, can only be 
conjectured. We might assume a simple stimulation of ferment 
action by mere contact. That it may become very pronounced, is 
evident from the action of borax, potassium cyanide and _potas- 
sium bromide in the case of trypsin and mercuric cyanide, ammonium 
arsenate, ferrous sulphate, potassium chlorate, sodium chloride, tartar 
emetic, and alkaloid salts in the case of the salivary ferment. 
As to the manner in which the various salts produce retardation 
of ferment action, it would appear as if many of the results obtained, 
could be accounted for only by assuming, in addition to the views 
already offered, a direct influence in many cases, either destructive 
or hindering, on the ferment itself. 
Those substances, which are particularly injurious to animal cells 
show in many cases no retarding action whatever, on the unformed 
ferments; this is particularly noticeable in the case of the arsenic 
compounds, which affect the ferments only as the solutions become 
acid. On the other hand, certain of the metallic salts are alike inju- 
rious to both and doubtless for the same reason, viz: on account of 
their power of combining with albuminous matter, which fact applies 
with equal force to the vegetable organisms (organized ferments). 
Nearly all germicides act injuriously on the unformed ferments. 
Many salts, however, well known as antiseptics, are without injuri- 
ous action, except when present in large quantity; notably borax in 
the case of trypsin or boracic acid in the case of pepsin-hydrochloric 
acid. 
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