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



on water in such a manner as to just immerse that portion of the 

 endosperm which had been in contact with the embryo. 



This method really affords much greater i'aciliiies for outward 

 diffusion from the endosperm than does Hansteen's plan of fixing the 

 degermed seeds on small columns of plaster partially immersed in 

 water, and it is also free from the objection of any possible disturb- 

 ing influence due to the solubility of the plaster. Moreover, the 

 mica-raft method is easier of manipulation, and whilst giving per- 

 haps better facilities for sterilisation, also allows the detection of the 

 very first appearance of micro-organisms. 



The barley used in our experiments was Hordeum vulgare (var. 

 distichon), derived from two sources. One, with which most of the 

 work was done, was a well-matured Chilian barley, of the Chevalier 

 type, the other an English Chevalier barley grown on light land in 

 Northamptonshire, both samples being well matured and well har- 

 vested. 



It will be convenient in the first place to consider the visible 

 changes which can be induced in the endosperm when this is com- 

 pletely deprived of its embryo, and is put under such conditions as 

 to ensure the speedy removal of any soluble and diffusible products 

 which may result from any self-digestive processes initiated by any 

 portion of the endosperm tissue. 



Some of our experiments on this point were made in the following 

 manner : 



The grain was, in the first place, steeped from one to two houra 

 in a 1 per cent, solution of copper sulphate, and after being 

 washed with sterilised water was steeped, also in sterilised water, for 

 a period of from twenty-four to forty- eight hours. From the corns 

 selected for experiment the palese and embryos were then removed 

 with antiseptic precautions, this process being conducted in a glass- 

 fronted sterile operating chamber, furnished with " sleeves." The 

 degermation was performed with a small scalpel, taking care to 

 thoroughly remove all traces of the scutellum, and to lay bare the 

 " depleted layer " of the endosperm.* 



The isolated endosperms were then put in position in small holes 

 made in a very thin mica-raft which was floated on sterilised water 

 in a Petri's dish, or in a glass vessel of somewhat similar construction. 



* The nature and origin of this " depleted layer " can only be understood by fol- 

 lowing the developmental history of the endosperm and embryo, and this has been 

 so fully described in Ihe Brown and Morris paper of 1890 (loc. cit.) that it requires- 

 but a passing notice here. The "depleted layer" is made up of several thicknesses 

 of cell-membrane, which originally formed part of the amyliferous cells of the 

 young immature endosperm. During the later stages of development of the grain,, 

 and some time before maturation, the contents of these cells are used up for the 

 nutrition of the young embryo, but the cell-membranes persist and become squeezed 

 together by the gradual encroachment of the scutellum. 



