42 GENERAL ANATOMY OF THE TISSUES. 



and the solution of the solid contents which often occurs 

 in its neighbourhood, demonstrate. To assume with Schwann 

 a special metabolic force is incorrect, for, in the first place, the 

 causes of the metabolic phenomena are certainly very various ; 

 and, secondly, there is every reason to reduce them to known 

 molecular forces. Thus, for instance, even the action of the 

 nucleus 1 may not unfittingly be compared with the so-called 

 catalytic, or contact action, inasmuch as it is hardly at 

 all altered during the changes of the cells, and consists of 

 a nitrogenous substance, which like pepsin, (which is also 

 nothing but cell-contents), very readily produces a chemical 

 alteration in other substances. The relation of the cell-mem- 

 brane to absorption also, may even now be referred to the 

 general laws of imbibition and diffusion. 



[I here give two analyses as examples of the chemical com- 

 position of the cell-contents. The yelk of the hen's egg 

 contains: water, 48*55 ; casein, 13-93; albumen, mixed with 

 casein, 0892 ; albumen, 2-841 ; membranes of the yelk 

 vesicles, 0-459; fats, 31*146 (30-46 according to Gobley), 

 consisting of olein and margarin, 21-304; cholesterine, 0-438; 

 lecithin (containing phosphoric acid), 8-426; and cerebrin; salts, 

 1-523; a hundred parts of the ash yielded, potass, 8-60 — 8 - 93 ; 

 chloride of sodium, 912 ; phosphatic salts, 66-7 — 67*8; lime, 

 12-21 ; magnesia, 2-07 ; oxide of iron, 1-45 ; silica, 0*055. The 

 blood-corpuscles contain : water, 68-88; hsematin, 1*67; globulin 

 and membranes, 28*22 ; fat, - 23 ; extractive matters, 0'26 

 mineral substances (without iron), 0-81; of which, chlorine, 0-16 

 sulphuric acid, 0-006 ; phosphoric acid, 0-4 ; potassium, - 33 

 sodium, 0-10; oxygen, 0'06 ; phosphate of lime, 0-01 ; phosphate 

 of magnesia, 0-007. To these must also be added, free 

 oxygen and carbonic acid, which likewise occur in the yelk. 



We have here instances of cells containing much protein, 

 and especially fat, and may consider them to be fair examples 

 of this kind of cell. The comparison of the contents of these 

 cells with the plasma of the blood, out of which those of the 



1 [This " action of the nucleus" is a wholly hypothetical though a very general 

 assumption. It is important to hear in mind, on the contrary, that there is every 

 reason to helieve that the molecular and chemical changes of the cell -membrane 

 and the nucleus are independent of one another. — Eds.] 



