344 OF THE PRIMARY TISSUES OF THE HUMAN BODY. 



According to M. Fremy, the Phosphorus is combined with part of the fatty 

 matter; and forms with it two peculiar fatty acids, termed by him the Cerebric 

 and Oleoplwsphoric ( 44). Cholesterin has also been extracted from the brain 

 by M. Fremy in considerable quantity; and is perhaps to be regarded as one of 

 the products of its disintegration ( 43). The proportion of Fixed Salts is 

 about 3 parts in 100 of dry Cerebral matter; the nature of these has not yet 

 been satisfactorily determined, but they seem to be chiefly alkaline phosphates 

 and carbonates. According to Lassaigne, the chemical composition of the 

 "cortical" and " medullary" substances of the brain is essentially different; the 

 former containing 85 per cent, of water, whilst the latter has only 73; the cor- 

 tical substance having also 3.7 per cent, of a red fatty matter, of which the 

 medullary has scarcely any; and being almost entirely destitute of the white 

 fatty matter, which exists in large proportion in the latter. The Albuminous 

 matter in the above analyses probably constitutes the walls of the nerve-cells 

 and nerve-tubes (as well as of the capillary bloodvessels), and that portion of 

 their contents which is represented in the nerve-tubes by the "axis-band;" whilst 

 the phospJiorized fats seem to form the " white substance of Schwann" in the 

 tubular fibres, and a considerable part of the contents of the vesicles. It will 

 be remarked, that the amount of phosphorus is the greatest at the period of 

 greatest mental vigor; and that in infancy, old age, and idiocy, the proportion 

 is not above half that which is present during the adolescent and adult periods. 

 346. The Nervous System is very copiously supplied with Bloodvessels; the 

 arrangement of which varies according to the form of the elementary parts in 

 which they are distributed. Thus, in the Vesicular substance of the nervous 

 centres, the capillaries form a minute network (Fig. 114), in the interstices of 

 which the ganglionic cells are included. In the Fibrous substance, the capil- 

 laries are distributed much on the same plan as in Muscular tissue (Fig. 101); 

 the network being composed of straight vessels, which run along the course of 

 the fibres, passing between the nerve-tubes, and which are connected at intervals 

 by transverse branches. And at the sensory extremities of the nerves, we find 

 loops of capillaries (Fig. 115) arching over their terminal and probably looped 

 filaments. The Braiit of Man, taken en masse, has been estimated to receive one- 

 sixth of the whole amount of blood, although its weight is not usually more than 

 one-fortieth part of that of the entire body. Whether or not this estimate be pre- 

 cisely correct, there can be no doubt that it receives far more blood than any other 

 part containing the same amount of solid matter. Now this copious supply 

 of blood evidently has reference to two distinct objects ; first, to supply the ne- 



Fig. 114. Fig. 115. 



Capillary network of Nervous Centres. Distribution of Capillaries of the surface 



of the Skin of the finger. 



cessary conditions for the action of the Nervous system ; and, secondly, to main- 

 tain its nutrition. Many circumstances lead to the conclusion that, in the Nerv- 

 ous as in the Muscular system, every vital operation is necessarily connected with 



and other chemists give a much higher proportion to the Phosphorized Fat, and a much 

 smaller one to the ill-defined compounds represented by the designation Osmazome. 



