Green. — On Vegetable Ferments. 1 1 3 
it is the custom of dairymen to put this plant into milk to set 
the curd ready for cheese-making. The active principle seems 
to be located in the flowers, though the whole plant is used. 
The power of curdling milk was stated by Linnaeus 1 to 
exist in the leaves of Pingnicula vulgaris , which he says were 
used for that purpose by certain Lapland tribes. Pfeffer says 
that they are also used in the Italian Alps to the same end. 
Darwin noted that the secretion of the glands of Drosera had 
the same power 2 . The latex of Carica Papaya , the bast of 
the stem of Clematis Vitalba , and the petals of the artichoke 
( Cynara Scolymus), also curdle milk, when allowed to remain 
immersed in it. 
The ferment has been extracted in recent years from a 
large number of seeds, some before and others during germi- 
nation. The fullest account of its properties has been given 
by Lea 3 , who prepared it from the resting seeds of Withania 
coagulans , a shrub which grows freely in Afghanistan and 
Northern India. Withania is a genus of the natural order 
Solanaceae, and has a capsular fruit, containing a large number 
of small seeds. From these it can be extracted either by 
glycerine or by a moderately strong solution of common salt. 
It is destroyed by boiling, but it can withstand a moderately 
prolonged exposure to alcohol. Its activity is about the same 
as that of most commercial samples of animal rennet. 
Martin 4 has shown that commercial papain contains rennet, 
but he does not speak of its situation in the plant. 
During the last few years the writer has met with vegetable 
rennet in the seeds of Datura Stramonium , Pisum sativum , 
Lupinus hirsutus , and Ricinus communis 5 , in the two former 
in the resting, and in the two latter in the germinating condi- 
tion. In Ricinus it does not exist in the resting state, but 
the seed will then give up to an appropriate solvent a principle 
in which the milk-curdling power can be developed by warm- 
1 Flora Laponica, 1737, p. 10. 
2 Insectivorous plants, 2nd edn., p. 94. 3 Proc. Roy. Soc. 1883. 
4 Journal of Physiology, VI, p. 340. 
5 Green, On the germination of the Castor-oil plant, Proc. Roy. Soc., vol. XLVIII, 
p. 391- 
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