REPORT ON ANIMAL PHYSIOIiOGY. 119 



homogeneous corpuscle comes in contact w ith water or an 

 acid, then first a change is effected ; the density increas- 

 ing towards the centre, and the colour, at first difi'used 

 through the whole mass, being then confiTied to the surface. 

 But however this may be, whether the nucleus have pre- 

 existed or be now first formed, it is not soluble either in 

 water or in dilute acetic acid, whilst the external portion 

 with the colour is gradually removed by this. This has 

 been pointed out by Miiller ^vith great precision in his late 

 work : the subject of his examination, principally, was the 

 blood of the Frog. 



Berzelius refers the insolubility of the corpuscles in serum to 

 the albumen which it contains : but this is not the only cause. 

 J. Miiller rather considers it to be an effect of the salts which 

 the senuu holds in solution ; for he found, that on adding to a 

 drop of Frog's blood under the microscope a drop of a solution 

 of yolk of egg in water, the corpuscles lose their form ajid be- 

 come round as quickly as in water, whilst a drop of a solution 

 of such a salt as does not separate the blood (as subcarb. po- 

 tass.) causes no such change to be effected. 



It has been stated by some that iron does not exist in greater 

 quantity in the cruor of the blood than in its other essential com- 

 ponents. Engelhardt has discovered a remarkable property of 

 chlorine, confirmed by H. Rose, by which the incorrectness of 

 that opinion has been proved, and the conclusion of Berzelius 

 established, viz., that all the iron of the blood belongs to the 

 cruor. The chlorine precipitates the animal matter from its solu- 

 tion in Mater, and at the same time deprives it of the lime, soda, 

 phosphorus, iron, which may have been connected with it. The 

 liquor being strained, the oxide of iron may be precipitated by 

 ammoiua : but that precaution is necessary, for otherwise, the 

 ammonia redissolves the organic matter, and the iron recom- 

 bines with it. Engelhardt could obtain no iron from similar 

 operations with serum and fibrin, though he did all the otJ cr 

 salts ; and there was no ash left on combustion. 



Berzelius 's estimate of the quantity of iron in the ash of the 

 cruor was confirmed by these experiments. Of the entire blood 

 metalUc iron forms only one part in 1000. 



It is yet undetermined whether the iron exists in the corpus- 

 cles of the blood ui its reguline form or as an oxide, Engel- 

 hardt and Berzelius supporting the former opinion, and H. Rose 

 and Gmelin the latter. For the former opinion it has been con- 

 tended, that chlorine has a strong affinity for the metals, but 

 none for their oxides ; and that the oxide of iron, if present, 

 would be dissolved by the mineral acids. But in Engelhardt's 



