THE RESERVE MATERIALS OF PLANTS. 73 



increases with the greater development of the plant, and in 

 being frequently plentiful in parts that are thrown off from 

 the latter, such as old leaves, the coats of fruits, seeds, etc., 

 and in regions withdrawn from active metabolism, such as 

 bark and to a less degree epidermis. In a further paper 

 Waage and Nickel suggest that it may possibly be a source 

 of tannin, as the latter is generally found in the same 

 parts as phloroglucin (74). Tannin does not appear, how- 

 ever, to give rise to phloroglucin. 



Like tannin, therefore, phloroglucin appears to be on the 

 whole an accessory product and only rarely to act as a 

 reserve material. The compounds of it which contain 

 sugar, i.e., the phloroglucosides, may serve as such, yielding 

 sugar on their decomposition. 



In certain cases the alkaloids appear to serve as reserve 

 materials, though their value in this direction is probably 

 but slight. Many seeds which contain them in some con- 

 siderable quantity lose them during germination, and other 

 bodies, principally amides, replace them in the developing 

 embryo or young seedling. This is especially the case with 

 the seed of Lathyrus Sativus, an Indian species which 

 contains sometimes as much as '5 per cent, of its dry 

 weight of an alkaloidal product known as viciine (75). 



The possibility of alkaloids helping in such cases to 

 form albuminoid materials or proteids has been pointed out 

 by Jorissen (76) in his discussion of the chemical processes 

 incident to germination, in which he claims for them a 

 certain value as reserve materials. Heckel [jj) comes to 

 the same conclusion. He carried out experiments with 

 Sterculia acuminata, Strychnos Nux-vomica, Physostigma 

 venenostim, and Datura Stramonium, and found in all these 

 cases that during germination the greater part of their 

 alkaloidal principles disappears. He claims that this 

 disappearance is due to a transformation into assimilable 

 substances under the influence of the embryo. If the 

 latter be extracted from the seeds, and they be then sur- 

 rounded by or buried in moist earth, the alkaloids remain 

 for a considerable time unchanged. 



The conclusions of Jorissen and Heckel are disputed by 



