BULLETIN OF THE BUSSEY INSTITUTION. 39 
Probably there are other Reserve Foods in Trees beside Starch 
and Mannan. 
The question what kinds of reserve foods are stored in trees 
that contain little starch and no mannan is still an open one. 
As has appeared from experiments described on pages 391, 443, 
448, and 465 of Volume II of the Bussey Bulletin, I have been un- 
able to detect much if any galactan in the wood of trees or enough 
starch to account for the abundant growth of leaves, ete., in the 
spring. The practical absence of xylan (wood gum) from the 
wood of coniferous trees in which mannan abounds and the pres- 
ence of much xylan in the wood of trees that carry no mannan, 
naturally suggest the thought that xylan might perhaps be an 
important kind of reserve food for the trees in which it occurs. 
But there are a number of considerations that weigh against 
this idea, — notably, the fact that xylan is not a fit food for 
animals, while mannan and starch are both excellent, and that 
experiments have not shown that xylan supplies food to the young 
plant at the moment of germination, as starch and inuline, man- 
nan and galactan do. The comparative indestructibility of xylan 
when wood or the like is left to decay in the soil, serves to 
emphasize the non-physiological attributes of this substance. It 
appears, indeed, that xylan is probably less important than cellu- 
lose as a means of feeding plants, — that is, as affording a supply 
of reserve food. 
In respect to many seeds, — such as pine seeds, for example, — 
it is known that. fatty and oily matters play a highly important 
part for feeding the young plant at the moment of germination. 
But as regards the actual wood of trees, I cannot but feel for my 
own part that it will be discovered some day that there is often 
contained in it another ‘‘ hemicellulose,” comparable to starch and 
mannan (and to inulin and galactan also), which serves as these 
substances do as reserve food for the production of leaves and 
new wood in the spring. 
It is noticeable that the finding of mannan in the wood of sugar- 
maple trees— which yield great quantities of sucrose at the moment 
when vegetation is renewed in the spring — goes to show that 
there must be a peculiarly intimate connection between these two 
substances. I+ may well be argued that the easy conversion of 
