TISSUES OF THE BOD!. 121 



Besides this, another matter belonging to the albuminoid group is 

 generally present, namely, the "serum-casein" of Panum; yet, as 

 we have already seen ( 11), it is probably nothing else than Schmidt's 

 fibrinoplastin. 



As to the fats contained in serum, very little is at present known. 

 They occur for the greater part in the state of soap, and dissolved; more 

 rarely suspended in the form of fine molecules. Should they become 

 unusually abundant in the latter form, a cloudy opalescent appearance may 

 be communicated to the blood, although this is more frequently the effect of 

 a molecular precipitation of some albuminate. Moreover, it appears to 

 be the ordinary fatty acids which enter into the composition of the 

 serous fats, and we are warranted in accepting the presence of oleic, 

 palmitic, stearic (and margaric T) acids here ( 17). Further a peculiar 

 substance, cholestearin, already mentioned ( 21), is to be found in small 

 quantity in the plasma. 



Turning now to the remaining and better known constituents of plasma, 

 which may be regarded for the most part as products of decomposition, 

 we find their number very considerable, owing to the nature of the fluid. 

 The following notes may be said to contain almost all that is at present 

 known about them. 



Among the organic acids the existence of lactic acid in healthy blood 

 is not yet entirely beyond doubt, but it has been found in the latter under 

 abnormal conditions. Blood may also contain formic acid from the group 

 of fluid fatty acids. Acetic acid has been remarked after indulgence in 

 alcohol ( 16), and succinic in the blood of phytophagous mammals ( 24). 



The non-existence of taurocholic and glycocholic acid in the plasma is 

 again of the highest physiological importance, whilst, on the other hand, 

 uric acid is met with ; the existence of hippuric remains doubtful ( 26). 

 Among the organic bases we must accept urea, kreatin, kreatinin (?); 

 hypoxanthin, and probably' also xanthin, as being many of them present 

 in the fluid under normal conditions, a series which will probably be 

 enlarged in the next few years. Leucin and tyrosin only appear patho- 

 logically ; they may occur in the blood during diseases of the liver. In 

 addition to these substances we have grape sugar also (belonging to the 

 group of hydrocarbons) as a constituent of plasma (Bernard and C. 

 Schmidt) : it is partly introduced as such into the system, and partly 

 formed in the liver. This substance, as Lehmann and Bernard have 

 shown, is not to be found at all, or only in traces, in the blood of the 

 vena porta, whilst that of the hepatic vein is rich in it. Milk sugar, on 

 the contrary, is probably absent ; inosite has not been observed. 



Finally, there exists an unknown colouring matter in the liquor 

 sanguinis, which gives rise to its pale yellow tint. The pigmentary 

 matters of the bile are absent here, on the other hand, in its normal 

 condition (at least usually). As to the extractives, their amount in the 

 plasma is greater than in the cells. 



Ko\v, when we come to consider the mineral matters of the plasma, we 

 find them essentially different in quantity from those of the blood- 

 corpuscles. The proportion of chlorine is more considerable here than in 

 the cell, but that of phosphoric acid, on the other hand, smaller ; and 

 whilst the amount of potash exceeded that of soda in the cell, the case is 

 completely reversed in plasma, the quantity of soda salts, and more 

 especially of chloride of sodium, preponderating in the latter. 



Further, the liquor sanguinis contains bicarbonate of soda, a small 



