12 
Vines.— The Proteases of Plants ( VI). 
enzymes of plants are tryptic ’. I extended my observations ( 14 , March 
1902) to other parts and secretions of plants, [such as the juice of the Pine-apple 
{Ananas sativus), the latex of the Papaw {Carica Papaya ) and of the Fig 
{Ficus Carica), Malt {Hordeum sativum ), and Yeast {Saccharomyces Cere- 
visiae ), and found in every case that tryptophane was one of the products of 
digestion, a proof that the digestion had been ‘ tryptic ’ in character, and 
that all the enzymes were active in acid medium. The conclusion that 
I drew from these facts was £ that the proteolytic enzymes of plants in 
general are essentially tryptic ’ ; adding that ‘ this statement will hold good 
until definite evidence is adduced to prove the existence of a “ peptic ” 
enzyme \ 
So far my investigations had been confined to parts or secretions of 
plants which were already known to have more or less definite digestive 
activity. I now turned my attention to the question of the possible presence 
of proteolytic enzymes in plants in which they had not yet been detected 
( 15 , Jan. 1903). 
In the first set of these experiments, Witte-peptone was the material 
for digestion ; the production of tryptophane was effected as the result of 
the action of the following substances : tissue of the Mushroom {Agaricus 
campestris) ; watery extract of Green Peas {Pisum sativum) ; extract of 
‘germ’ of Wheat {Triticum vulgare) ; the expressed juice of the Melon 
{Cucumis Meld), of the Cucumber {Cucumis sativus ), and of the Vegetable 
Marrow {Cucurbita Pcpo var. oviferd) ; watery extract of the Banana {Musa 
Sapientum) ; the juice of the Tomato {Ly coper sicum esculentum) ; the rind 
of the Apple {Pyrus Malus), and of the Orange {Citrus Aurantium) ; the 
juice of the Grape ( Vitis vinifera) ; extract of the laticiferous shoots of 
Euphorbia Characias ; the laticiferous leaves of the Lettuce {Lactucasativa ) ; 
the stems of Dahlia and of Mirabilis ; the leaves of Spinacia oleracea , of 
the Cabbage {Brassica oleracea), of a Grass {Holcus mollis), of a Fern 
{Scolopendr him vulgare), and of several other plants ; the bulbs of the Tulip, 
the Hyacinth, and the Onion {Allium Cepa) ; the tubers of the Potato {Sola- 
tium tuberosum) and of the Jerusalem Artichoke {Helianthus tuber osus) ; the 
roots of the Turnip {Brassica Rapa), the Tomato, the Vegetable Marrow, 
the Carrot, the Beet, and others. 
Having shown that these various parts of plants possessed the property 
of digesting Witte-peptone, I proceeded, in the next place, to ascertain if 
any of them also possessed the power of digesting fibrin. In this way I was 
able to add to the list of plants known, at that time, to digest fibrin, the 
following : the juice of the Cucumber and of the Melon ; the tissue of the 
Mushroom : the bulb of both the Tulip and the Hyacinth, but only in 
alkaline medium. I entirely failed to obtain any evidence of the capacity 
of ordinary foliage-leaves to digest fibrin. 
The conclusions that I drew at the time are as follows : ‘ I have 
