118 PHYSIOLOGY OF NUTRITION. 



The protoplasm of the individual cells of the parenchyma 

 appears smooth in outline at places where it bordered on a cell- 

 wall provided with very fine pores ; it shows thicker or thinner 

 processes where the adjacent cell-wall possessed wider pits. The 

 protoplasmic processes of neighbouring cells correspond with one 

 another. If we consider the swollen closing membrane separat- 

 ing two specially broad plasmic processes, directed towards each 

 other, we find running between them a number of extremely fine 

 granular threads. These are the plasmic filaments, which connect 

 the living protoplasm of the two cells. Where the adjoining 

 protoplasmic surfaces appear smooth, the middle layers of the 

 cell- wall between them are seen to be traversed, often throughout 

 their entire extent, by filaments, which at their middle appear 

 somewhat swollen. 



The protoplasm is always bounded on its surface, even when 

 surrounded by a cell-wall, by a hyaline layer, the ectoplasm 

 (Hautschicht) or hyaloplasm. This layer is, however, also present 

 at places where the protoplasm borders on the cell-sap. The bulk 

 of the protoplasm is formed by the granular layer, which is dis- 

 tinguished by its great richness in water and by its power of 

 movement, and further by the fact that it contains microsomata, 

 and often also chlorophyll bodies, etc. The hyaloplasm of most 

 cells is too delicate to be observed directly. In some cases, 

 however, its presence may easily be determined, and it is specially 

 well developed in the internodal cells of Nitella, a genus of AlgaB 

 of which representatives may frequently be met with, vigorously 

 developed, in waters poor in lime. The masses of the granular 

 layer of the protoplasm are here in active rotation, whilst the 

 hyaloplasm does not share this movement. 



I have often and emphatically pointed out 2 that there is no kind 

 of identity between dead and living proteid molecules of the proto- 

 plasm. Certain observations of Loew and Bokorny, 3 which we 

 must consider in some detail, are in harmony with this view. We 

 prepare a solution of potash of 1'333 sp. gr., and add 13 c.c. of it 

 to 10 c.c. of ammonia of O960 sp. gr. The mixture is made up to 

 100 c.c. We further prepare a 1 per cent, solution of Silver nitrate. 

 For use, 1 c.c. each of the potash-ammonia fluid and the Silver 

 solution are mixed, and diluted up to 1 litre. We now place in 

 a litre of the alkaline Silver solution a few filaments of Spirogyra 

 (other cells show the reaction in question in the same manner, but 

 not so clearly), and allow them to remain in it for some time (at 



