THE CHEMISTRY OF COOKERY. 819 



animals, by which the whole body is made one inter-related unit, may 

 be but a final outgrowth of the fibrillar-cell system. The fibril reticu- 

 lum of the isolated cell becomes the nerve reticulum of the complex 

 body, which is virtually converted into a single cell, with its intricate 

 network of fibers,* 



»•> 



THE CHEMISTRY OF COOKERY. 



By W. MATTIEU WILLIAMS. 

 XLVIII. — THE WEAE AND TEAR OF THE BODY. 



IN the course of these papers I have repeatedly spoken of the nitro- 

 genous and non-nitrogenous constituents of food, assuming that 

 the nitrogenous are the most nutritious, are the plastic or flesh-building 

 materials ; and that the non-nitrogenous materials can not build up 

 flesh or bone or nervous matter, can only supply the material of fat, 

 and by their combustion maintain the animal heat. 



In doing so I have been treading on loose ground — I may say, on 

 a scientific quicksand. When I first taught practical physiology to 

 children in Edinburgh, many years ago, this part of the subject was 

 much easier to teach than now. The simple and elegant theory of 

 Liebig was then generally accepted, and appeared quite sound. 



According to this, every muscular effort is performed at the ex- 

 pense of muscular tissue ; every mental effort, at the expense of cere- 

 bral tissue ; and so on with all the forces of life. This consumption 

 or degradation of tissue demands continual supplies of food for its 

 renewal, and, as all the working organs of the animal are composed of 

 nitrogenous tissue, it is clearly necessary, according to this, that we 

 should be supplied with nitrogenous food to renew them, seeing that 

 the nitrogen of the air can not be assimilated by animals at all. 



But, besides doing mechanical and mental work, the animal body 

 is continually giving out heat, and its temperature must be maintained. 



* Within the last few years research into the conditions of plant-cells has led to the 

 interesting discovery that these cells are very generally connected by fine fibrils of proto- 

 plasm, in a manner somewhat similar to that which Heitzmann declares to be the general 

 rule in animals. Possibly this may prove to be a universal condition. Mr. Walter Gar- 

 diner, in a memoir read before the Royal Society, April 26, 1883, says: "Although I am 

 aware of the danger of rushing to conclusions, I can not but remark that when these 

 results — which were foreshadowed by Sachs and Haustein when they discovered the per- 

 foration of the sieve-plate — are taken in connection with those of Russow, it appears ex- 

 tremely probable that, not only in the parenchymatous cells of pulvini, in phloem paren- 

 chyma, in endosperm-cells, and in the prosenchymatous bast-fibers, is continuity estab- 

 lished from cell to cell, but that the phenomenon is of much wider if not of universal 

 occurrence." This condition, so commonly present in plants, has as yet not been widely 

 traced in animals, but may eventually prove to be equally general, as Heitzmann declares. 

 The connecting protoplasmic fibril may be the embryo stage of the nerve-fiber, and may 

 eerve to bring every cell in the body within the range of nerve influence. 



