HE. MATIN. 307 



cells, in the young blood-corpuscles of the amphibia [in their 

 embryonic state] we find not only roundish but also angular 

 granules soluble in ether, which can hardly be anything else than 

 stearin. Henle and H. M tiller refer the primary origin of the 

 colourless blood-corpuscles to the fat which is recognisable as a 

 fine granular (almost cloudy) matter in the minutest lacteals. We 

 have already mentioned that the fat stands in a certain relation to 

 the functions of the liver; the beautiful investigations of E. H. 

 Weber and Kolliker have, however, now demonstrated that large 

 quantities of blood-corpuscles are always formed in the liver in the 

 foetal state, and during the hybernation of certain animals, and 

 therefore at periods when this organ secretes little or no bile, but 

 when fat is accumulated in it. 



Moreover, an unprejudiced examination of the development of 

 the chick within the egg leads to the assumption that the fat takes 

 a part in the formation of haematin ; and if physiological facts can 

 be adduced in favour of this hypothesis, there are at all events no 

 chemical objections to it. As it is obvious that the colouring 

 matter can only be formed when there is free access of oxygen, 

 namely in the vessels, and as the oxygen doubtless contributes 

 materially to its production, we cannot suppose that it is formed 

 from protein, which is a substance rich in oxygen, or from sugar ; 

 hence there is hardly any other substance than the fat from which 

 a process of oxidation could yield haematin. 



Our present assumption of the formation of haematin from fat 

 is to be regarded merely as an hypothesis based on one or two phy- 

 siological facts, which may possibly admit of a very different inter- 

 pretation ; it is only intended to serve as a means of directing our 

 attention in a definite direction in the investigation of this subject. 



Uses. The constant occurrence of haematin in the blood- 

 corpuscles indicates that this body takes an important part in the 

 metamorphosis of the animal tissues. All sorts of conjectures have 

 been hazarded regarding its function in the blood, and it has been 

 especially supposed to be connected with the process of respiration. 

 In point of fact, however, it is unnecessary to consider any hypo- 

 thesis, until it has been satisfactorily ascertained whether the 

 hsematin in question actually stands in the same relation to the true 

 pigment of the blood as coagulated to non-coagulated albumen, or 

 whether artificially prepared haematin is altogether a product of 

 decomposition of the actual pigment. If hsematin has the same 

 composition as that which we prepare artificially, and if the only 

 difference be that it exists in a soluble form in the blood- corpuscles, 



x 2 



