556 LECTURE XXIII. 



The results obtained in the analysis of the blood of different species of 

 animals are given on pages 554 and 555, * now emphazing, however, that 

 the analyses of the ash have only a relative value, but on the other hand 

 such values may well serve, and in fact have served, as a foundation for 

 further inquiry, although the methods employed are not yet such that the 

 analytical results will prove fruitful in all directions. 



From the table it is evident that the serum from various animal species 

 is of much the same composition. There are, however, marked differences 

 in the composition of the blood as a whole, and of the blood-corpuscles. 

 It is interesting that the blood of related animals is very similar. This 

 is apparent when we compare, for example, the relative amounts of the 

 separate constituents of the blood-corpuscles of the carnivora with those 

 of the ruminants. It is certainly not without significance that the blood 

 of both these families contains considerable soda, while that of the horse, 

 pig, and rabbit contains none at all. Certain constituents, as, for example, 

 sugar, fat, and lime, are apparently wanting in the blood-corpuscles. It 

 is rather questionable whether we can assume that the substances are 

 entirely absent. The methods employed are not sensitive enough to make 

 such a decision possible. To be sure, the fact that this result has been 

 repeatedly obtained speaks in favor of its correctness. We may call 

 attention to the fact that quite recently glucuronic acid has also been 

 found in the blood-corpuscles. 



We should mention the fact that the amount of blood contained in dif- 

 ferent animals has been estimated. A sample of blood was taken from the 

 animal in question, after which it was bled to death, and the blood-vessels 

 washed out with water, until the latter came out perfectly clear and color- 

 less. The wash-water was mixed with the blood, collected, leaving out 

 the first sample, and the total volume estimated. Then the first sample 

 was diluted with water until it corresponded in shade with the other 

 mixture. In this way it was easy to compute the amount of blood con- 

 tained in the animal. 



This method is not very accurate, and there are several sources of error. 

 It is, in fact, impossible to remove all the blood from the body in such a 

 way. In the case of dogs the weight of the blood amounts to from seven 

 to nine per cent of the dog's weight, in rabbits the blood corresponds to 

 from five to nine per cent, while in man it is only from one-sixteenth to 

 one-thirtieth of the body- weight. 



In human beings, a cubic millimeter of blood contains on an average 

 5,000,000 red corpuscles in the case of males, and 4,500,000 in females. 

 There is usually one white corpuscle for every 350 to 500 red ones. Nat- 

 urally these values vary according to the blood-vessel from which the 



1 E. Abderhalden: Z. physiol. Chem. 25, 67 (1898). 



