198 
Parkin.—Observations on 
Bamber, resident in Ceylon, by means of Kjeldahl’s wet 
method, the amount of nitrogen found calculated out to 
about 2 per cent, of proteid. 
Castilloa. The proteid of the latex of Castilloa elastica has 
also been investigated to some extent by Biffen \ He 
found that the latex gives an acid reaction, and that on the 
addition of a little alkali it is coagulated. This he considered 
to be due to the nature of the proteid which exists as acid- 
albumen in the latex; on neutralization it comes out of 
solution and gathers together the caoutchouc particles into 
clots. 
Now the latex of the Castilloa introduced into Ceylon 
(C. Markhamiana) does not behave like this. On the very 
gradual addition of alkali to the latex or to the filtrate 2 of 
the latex no coagulation or precipitation occurs. Alcohol 
causes a coagulation of the latex and a copious precipitate 
in the filtrate, which is quite soluble again in water. 
Proteid is present in considerable quantity, about 4 per cent, 
being indicated by analysis. Coagulation is brought about 
neither by acids nor by boiling. Thus it looks as if the 
proteid belongs to the class of albumoses. At any rate the 
type of Castilloa introduced into Ceylon differs in this 
respect strikingly from that of the true Castilloa elastica 
examined by Biffen. 
When the latex of Castilloa is mixed with water and allowed 
to stand, in the course of an hour or two the caoutchouc 
particles have all floated to the top in the form of a thick 
cream. The diluted latex of Hevea , on the contrary, shows 
no sign of creaming, even when submitted to a low tem¬ 
perature. The difference is most likely due to the larger 
size of the caoutchouc globule in the case of Castilloa as 
compared with that of Hevea. 
The presence in latex of these most important plastic 
substances, proteids, is perhaps one of the strongest facts in 
support of the view that the laticiferous system takes part 
1 Biffen, loc. cit. 
2 The liquid part of the latex without the globules of caoutchouc. 
