Endosperm of Hordeurn vulgare during Germination. 21 



destroy the vitality of the germ, but that at least twenty-four hours' 

 immersion is required to permanently destroy the vitality of the 

 " aleurone-layer," and that if this is not perfectly effected, subse- 

 quent " grafting " experiments may suggest entirely erroneous con- 

 clusions. 



In the following remarks we shall refer to those endosperms which 

 have been thus treated with chloroform -water as "dead," whilst 

 those which have been merely soaked in water after degermation 

 we shall regard as " living." 



When "graftings " of embryos are made on living and dead endo- 

 sperms respectively, and these are placed under favourable conditions 

 for germination, very strongly marked differences are observable within 

 a few days, both in the rapidity of growth and general appearance 

 of the two sets of embryos, and in the nature and extent of the 

 concurrent changes in the endosperms. 



On the " living " endosperm the axial organs of the young 

 plant develop freely, healthy rootlets are protruded, and the freely 

 growing plumula has all the appearances of turgidity and firmness 

 incidental to good nutrition. Simultaneously with this development 

 cytohydrolysis commences under the " aleurone-layer," and, whilst 

 attacking the " depleted layer," progresses peripherally and distally 

 along the usual path in the endosperm. At the same time a distinct 

 and sometimes considerable amount of starch-erosion is noticeable 

 in the amyliferous cells immediately in contact with the " aleurone- 

 layer " of the proximal end of the grain, but this is entirely of a 

 " sub-aleuronic '' type (see antea), whilst the starch -erosion which 

 has taken place immediately under the scutellum of the " grafted " 

 embryo is wholly of the " pitted " or " sub-scutellar " type. 



The phenomena presented by the "grafting" on the "dead" 

 endosperms are, on the other hand, of a very different character. 

 Here the embryo is evidently under much less favourable conditions 

 for healthy growth, since the young plant is much smaller, the 

 tissues of its axial organs are flaccid, and there is very poor root- 

 development. At the same time it is also clear that the embryo is 

 deriving some nutriment from the dead endosperm and is increasing 

 in weight, a fact which can readily be proved by a comparison with 

 the development of excised embryos in water- culture on a porous tile. 



The internal changes which the dead endosperm itself undergoes 

 when in contact with the living embryo are very instructive, and a 

 careful study of them enables us, with certainty, to distinguish and 

 delimit the autonomous changes of the endosperm from those induced 

 by the embryo itself. Even after eight or ten days the dead endo- 

 sperms under these conditions exhibit no softening or cytohvdrolvsis 

 of the tissues immediately underlying the " aleurone-lajer," and 

 this layer remains firmly attached to the subjacent amyliferous cells. 



