DR. DUFFIN, ON PROTOPLASM. 951 
of a skeleton in the animal kingdom, and I recollect, in 
1837, Professor Grant, in his lectures at University College, 
drawing a comparison between raphides and the siliceous 
spicules of the sponges. When we consider the functions of 
the siliceous deposits in so large a number of plants, I think 
there can be little doubt that, in many cases, these mineral 
deposits perform the same functions im the plant as in the 
animal. At the same time, just as we find a large number 
of mineral compounds in plants which do not subserve the 
purposes of a skeleton, so in plants many of these mineral 
substances probably perform this and even more important 
functions in the life of plants. 
What these are it is for careful observation to point out. 
It is not sufficient that we know that certain mineral com- 
pounds are necessary for the life of plants, but what we 
require to know is how particular mineral compounds are 
necessary to the life of plants, and the nature of the vital 
processes which are thus affected by these agents. 
Some Account of Prororiasm, and the part it plays in the 
Actions of Livine Brines. By A. B. Durrin, M.D., 
Assistant-Physician to King’s College Hospital. 
Ir will not be seriously contested that, of the constituents 
of the cell, the so-called “ protoplasm”’ is deserving of particu- 
lar attention, from its liability to change, its activity, and the 
marked manner in which it participates in the vital pheno- 
mena of living structures. Since the publication of H. v. 
Mohl’s remarkable work, the botanists have long arrived at 
the conclusion that, not only the formation of the cell-mem- 
brane, but also the inner nutritional changes of the cell itself, 
primarily depend upon the protoplasma. 
As early as 1861* Max Schultze insisted upon the neces- 
sity of a modification of the views generally entertained re- 
specting the relation of the cell-membrane to the cell-con- 
tents, and to the so-called intercellular substance of animal 
structure, and he argued in favour of a higher position for 
that part of the cell which corresponds to the protoplasm of 
Mohl. He at the same period pointed out how materially a 
careful study of the phenomena presented by the pseudo- 
podia extended by the various Rhizopoda might assist m 
* “Ueber Muskelkérperchen,” Reichert u. Du Bois Reymond’s ‘Archiv,’ 
1861, 
