Notes. 
337 
the laticiferous system and the assimilating tissues, chemical methods 
had to be applied. 
So far the chemical side of the question appears to have been badly 
neglected, although it was attacked so long ago by v. Mohl b We 
may pass over the few analyses made of latex yielding economic 
products, and briefly notice that Weiss and Wiesner 1 2 have shown the 
presence of sugars in latex, and that Green 3 has examined its 
proteids. 
As the sugars are so intimately connected with assimilation, it was 
decided to estimate them in latex drawn from plants under varying 
conditions with regard to their capability for assimilation. 
The method employed was to take a known quantity of latex and 
remove the proteids by precipitation with excess of alcohol. After 
standing for a day, the solution was filtered off and evaporated to 
dryness over a water-bath. The sugars were then extracted from the 
resinous mass with warm water and estimated with Fehling’s solution. 
The precipitate was weighed as CuO. With ordinary care this method 
gives very constant results, which is a point of considerable value 
when working with small quantities of latex. Where tannins are 
present they should be extracted with hide powder or ethyl acetate ; 
but as the process leads to a certain amount of loss, it is as well to use 
latex free from them when possible. 
We will first examine the results obtained when assimilation is 
checked by darkening the plants. Four plants of Euphorbia 
pule her rima were placed in a dark room, and another set were kept 
in a greenhouse at a subtropical temperature. 
The undarkened plants showed the presence of sugars equivalent 
to -021 grms. CuO per c.c. After being darkened for a day the 
amount of sugar fell to -002 grms. CuO per c.c., and after another day 
no trace could be found. Euphorbia arborescens gave the same 
results. 
Judging solely from the bulk of the proteid precipitate, the proteids 
had also undergone a considerable diminution in quantity. 
If one may dismiss pathological changes due to abnormal con- 
ditions in this case, we may say that there is some definite connexion 
1 v. Mohl, Bot. Zeit., 1843, p. 553 et seq. 
2 Weiss and Wiesner, Bot. Zeit., 1861, p. 41 ; and 1862, p. 125. 
3 Green, Proc. Roy. Soc., 1886, No. 242, p. 28. 
