274 BLOOD. 



corpuscles are formed within the colourless ones, so that the latter 

 stand in the relation of parent-cells to the former. But as this 

 subject belongs less to physiological chemistry than to pure 

 histology, the present remarks must suffice until we are able to 

 bring chemistry to our aid in explaining the progressive and 

 regressive development of the blood-cells. 



As yet we know very little of the manner in which the blood- 

 corpuscles act in the living blood, the objects they fulfil or the 

 results of their chemical metamorphoses. But our deficiency in 

 positive knowledge has here been liberally supplied by hypotheses, 

 whose value we will briefly consider. As might be expected, the dis- 

 covery of these peculiar molecules in the blood led to that false and 

 illogical application of the word "life" which even now is not 

 wholly banished from physical physiology. The very vagueness 

 of the term " life " served as a cloak for everything that did not 

 readily admit of being referred to physical or chemical agencies. 

 The molecules of the blood were supposed to be endowed with 

 individual vitality like the infusoria, for which they were even 

 mistaken by some observers (Eble and Mayer), in proof of which 

 assertion it was maintained, according to Czermak, Treviranus and 

 Mayer, and still more recently by Emmerson and Reader, that 

 they exhibited a spontaneous motion. Very recently, moreover, one 

 of our most distinguished chemists has been erroneously led by 

 his experiments to believe in a peculiar vital activity of the blood- 

 corpuscles. Dumas could not resist advancing the assertion that 

 the blood-corpuscles possess a certain respiratory activity which may 

 occasionally be reduced to actual asphyxia. It will be a sufficient 

 refutation of this view, if we mention that Dumas was led to this 

 conclusion merely by making the well-known observation that 

 blood-cells, when treated with neutral alkaline salts, cohere when at 

 rest, assume a darker colour and begin to be decomposed at a 

 moderate temperature; while this alteration occurs at a later period, 

 when the blood which has been acted on by salts is frequently 

 shaken. Dumas thought that the access of oxygen, brought about 

 by shaking the blood-corpuscles, caused them to retain their vitality 

 for a longer period ; but when they are shaken with nitrogen or 

 hydrogen gas, they do not sooner become dark than when they are 

 shaken with atmospheric air ; hence it is merely the motion which 

 retards the cohesion and further decomposition of the blood-cells. 

 In order to avoid misconception, we would, however, observe in 

 reference to the vitality of the blood-cells, that if by the term " life' 5 

 we mean simply a group of physical and chemical agencies, having 



