VOLUME XXXIX NUMBER 5 
HOTANICAL (GAZETTE 
MAY, 1905 
ON PROTEOLYTIC ENZYMES. I. 
ARTHUR L. DEAN. 
NUMEROUS investigators have studied the proteolytic enzymes 
in plants and their work appears to have been carried on from two 
different points of view. The physiological chemists working with 
vegetable proteases have made careful studies of the products and 
nature of the action of enzymes of marked activitity. Of such 
work, the investigations carried on by CHITTENDEN and his pupils 
on bromelin are excellent examples. In studies of this kind the 
enzyme is the important thing, the réle of the enzyme in the physi- 
ology of the plant is secondary. On the other hand, the studies 
of plant physiologists have been directed less to working out the 
nature of the enzymes and more to locating them and to discovering 
their function in the life of the plant. Of such researches the inten- 
sive studies of BUTKEWITSCH on germinating seeds, and the extensive 
ones of VINEs on all sorts of plant tissues, are good illustrations. 
Looking at the subject from the point of view of plant physiology, 
we may conceive of proteolytic enzymes as being digestive, 7. ¢., 
acting on stores of proteid, as in germinating seeds; or metabolic, 
* €., acting on the proteids in the life of the vegetable cells. The 
idea of enzymes digesting the reserve proteids was the first to occur 
to physiologists. Acting on the hypothesis of the existence of such 
snzymes, numerous investigators have examined germinating seeds, 
"sing a variety of methods, and obtaining results which have not 
always been in harmony with the hypothesis or with each other. 
The view that wherever we find proteids in an organism, there 
we should always find a proteolytic enzyme, is not a new one; the 
€xperimental facts to support such a conception have been slow 
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