Dkcembeb 12, 1902.] 



SCIENCE. 



935 



sperm, under the condition of non-removal 

 of the products of the decomposition, it 

 did appear in the cells in the form of 

 small grains, though not till after several 

 days had elapsed. Van Tieghem also ob- 

 served that the progress of the decomposi- 

 tions could be arrested and the endosperms 

 made to reassume a quiescent condition, 

 and that then the aleurone grains again be- 

 came formed, though in less quantity than 

 before. 



In some experiments on Ricinus which I 

 carried out in 1889 I found much the same 

 sequence of events as Van Tieghem had 

 described. The endosperm unquestionably 

 became the seat of a renewed metabolism, 

 in the course of wliich many interactions 

 between the various reserve materials be- 

 came noticeable. It was remarkable that 

 the activity of this metabolism was much 

 more pronounced when the embryo or parts 

 of it were left in contact with the endo- 

 sperms. 



An observation of a similar character 

 has been made by Haberlandt and by 

 Brown and Morris in the case of the seeds 

 of grasses. The conversion of the reserve 

 cellulose of barley grains has been shown 

 by these observers to be the result of the 

 action of an enzyme cytase, which is 

 secreted largely by the so-called aleurone 

 layer, which is found surrounding the en- 

 dosperm, immediately underneath the testa. 



Recently my own work has been bearing 

 on this question, particularly as regards 

 the behavior of the seeds of Ricinus during 

 germination. The reserves of this seed are 

 mainly composed of oil and aleurone grains, 

 hardly a trace of carbohydrates being pres- 

 ent. At the onset of germination there is 

 a remarkable appearance of both cane sugar 

 and glucose, which increase as the oil di- 

 minishes. The old view advanced to ex- 

 plain this fact has been the transformation 

 of the oil directly into the sugars or one 

 of them, a theory which it was difficult to 



reconcile with the chemical possibilities of 

 oil. I have found that side by side with 

 the appearance of the sugar we have also 

 the formation of a considerable quantity of 

 lecithin, a fatty body containing nitrogen 

 and phosphorus. The seed contains a 

 comparatively large amount of phosphorus 

 in the form of the well-known globoids of 

 the aleurone grain, a double phosphate of 

 calcium and magnesium. The occurrence 

 of this body points to a considerable inter- 

 action of various substances existing in the 

 seeds, the phosphorus apparently coming 

 from the globoids and the nitrogen from 

 the proteids. Instead therefore of the fat 

 being transformed into sugar it seems cer- 

 tain that a very considerable metabolism is 

 set up, in which the various constituents 

 of the endosperm interact very freely to- 

 gether. I am informed by Mr. Biffin, who 

 has investigated the histological changes 

 accompanying the germination, that the 

 protoplasm of the endosperm cells appears 

 to increase in amount very greatly during 

 the early stages. The observations suggest 

 a very vigorous resumption of metabolic 

 activity by the cells of the endosperm, in 

 the course of which the various reserves are 

 brought into relation with the living sub- 

 stance of the cells and a number of new 

 products are formed to minister to the nu- 

 trition of the growing embryo. The for- 

 mation of the sugars may more probably be 

 referred to the renewed activity of the pro- 

 toplasm of the parent gametophyte than to 

 a direct transformation of the fat under the 

 influence of the embryo. Further re- 

 searches upon a large variety of seeds ap- 

 pear necessary to give us a true idea of 

 the chemical processes of germination. 

 What now appears probable in the case of 

 fatty seeds may prove to be true also in the 

 case of those which have other varieties 

 of reserve material. 



I have already alluded to the problems 

 concerning the electrical phenomena pre- 



