4 Messrs. Brown and Escombe. On the Depletion of the 



original paper, and here merely quote the general conclusions which 

 were drawn from them. 



Although the peripheral layer of the endosperm, the so-called 

 "aleurone-layer," or " Kleberschicht," undoubtedly consists of living 

 cells, no evidence could be obtained of the existence of any 

 residual vitality in the amyliferous cells, which constitute by far the 

 greater portion of the endosperm. 



No changes were observed in the isolated endosperms in the 

 direction of self-depletion which were comparable in intensity with 

 those produced when the embryo was attached ; and when those 

 changes did occur they were always preceded by an invasion of 

 bacteria and moulds in the culture-medium, the disintegration and 

 dissolution of the endosperm-contents in such cases proceeding in 

 such a manner as to suggest that they were conditioned entirely 

 by the organisms. 



When living embryos were " grafted " on endosperms which had 

 remained in alcohol for six months, and in which it was then 

 reasonable to suppose that any residual vitality had been effectually 

 destroyed, all the usual phenomena incident to normal germination 

 were observable in those endosperms. Hence it was concluded that 

 the idea of any co-operation on the part of the endosperm-cells was 

 superfluous, and that the determining factor in the normal endo- 

 spermous changes is the embryo itself, which, by independent ex- 

 periment, had been shown to possess the power of dissolving 

 starch and of initiating those phenomena of cytohydro lysis which 

 are amongst the earliest exhibited in natural germination. Accord- 

 ing to this view the endosperm of Hordeum, and probably of all the 

 Grasses, is, as far as its starch- containing cells are concerned, a dead 

 storehouse of reserve material, whose stores can be converted to the 

 use of the plant by the action of the embryo only, and that this, 

 for a limited period of its existence, lives a truly saprophytic 

 life. 



These conclusions are in accord with the views of Van Tieghem, 

 that, whilst an endosperm, such as that of Ricinus, containing oil 

 and aleurone as reserve materials, is endowed with a vital activity 

 of its own, by virtue of which it is capable of digesting the reserve 

 material in preparation for the embryo, the endosperm of Eeeds, 

 whose reserve materials, on the other hand, consist of starch and 

 cellulose, remains passive during germination, the digestion of its 

 reserves being in this case effected by the embryo. 



Two years after the appearance of the above-mentioned paper, 

 Proffer gave a brief description of some work by B. Hansteen, 

 ' tj ber die Ursachen der Entleerung der Reservestoffe aus Samen,'* 



* 'Ber. der Itouigl. Sachs. Gesellscli. d. Wissenschaften zu Leipzig,' 1893,. 

 p. 421. 





