of Laticiferous Tubes * 167 
In fact, all the starch is used except that in the laticiferous 
tubes (sieve-tubes ?), and the guard-cells of the stomata. This 
suggests that the starch may have a local use inside the tube. 
Treub, in his cautious paper, says that his results might be 
thus explained, but that it is difficult to conceive of any such 
local use. The starch might easily, directly or indirectly, give 
rise to tannin , 1 resin, organic acids, etc. And recently Stahl, 
in his admirable work ‘Pflanzen und Schnecken,’ has suggested 
a use for some of these bodies. He conclusively proves that 
many substances, such as tannin, acid secretions, bitter bodies, 
ethereal oils, etc., protect plants from the attacks of animals. 
He supposes that this protective function often belongs to 
laticiferous tubes. This would explain the frequent approach 
of the tubes to the surfaces. It cannot be pretended that this 
is a complete explanation of the function of laticiferous tubes. 
It seems impossible to discover what is their function, or to 
ascertain if there is one function common to all laticiferous 
tubes, until microchemical methods are vastly improved, or 
until analyses of latex in its various stages are made. 
I take the opportunity of thanking Prof. Schimper, at whose 
suggestion this work was undertaken, for his advice. He also 
very kindly handed over to me the material which he had 
collected and prepared in Brazil. 
1 For instance see observations of Briosi (quoted in Mayer’s Agriculturchemie), 
and Schulz, in Flora, 1888, who show that tannin may replace starch. See also 
Hanstein in Bot. Zeit. 1868, and Dippel (quoted in Haberlandt’s Anat. p. 333), with 
reference to resin. 
N 
