THE BLOOD-CORPUSCLES. 159 



consist in the reciprocal action of the cells contained in it, and the 

 plasma surrounding them. In every investigation it is necessary 

 and in the consideration of this most important of all the fluids, 

 it is especially the case that we should, before all things, make 

 it perfectly clear from what point the inquiry should be undertaken. 

 The physiologist is aware that in the blood, the cells and the 

 intercellular fluid uninterruptedly act upon one another, without 

 however the reactions being perfectly equalised ; we know that the 

 intercellular fluid acts on the cells, and that the contents of the 

 latter react on the former ; in a word, we know that the con- 

 tents of the cells and the intercellular fluid are different and hete- 

 rogenous; for if there were not a difference between them, no 

 reaction would be conceivable. 



Hence, like the fluid in which yeast-cells are developed, and 

 indeed like all germ-fluids, the intercellular fluid contains the 

 material from which the cells are formed, as well as the sub- 

 stances which are produced by the activity of the cells or their 

 metamorphosis and regressive formation. 



This is the point of view from which the physiologist would desire 

 that the investigation of the blood should commence ; for thus only 

 could fruitful results be expected. The chemist, however, whether 

 designedly or undesignedly, has failed in sufficiently separating these 

 different objects of investigation, and for the most part has treated 

 them simply as different constituents of one and the same fluid, 

 whilst he has regarded the most important morphological elements, 

 the most essential factors in the metamorphosis of the blood 

 merely as simple constituents of the collective mixture, and has 

 placed them in the same chemical category with fibrin and albumen, 

 after separating them, like the latter, from the particles with which 

 he presumes they are only mechanically connected and intermingled. 

 Such a chemical mode of treating the blood must be very detri- 

 mental to physiological progress, for the chemist is hardly able to 

 obtain in a perfectly isolated state, the substance which he regards 

 and calculates as dried corpuscles. Hence, in order not to be led 

 astray in our view of the composition of this animal juice by the 

 chemical difficulties of analysing the blood and of ascertaining its 

 constituents points which have been already often noticed in the 

 first volume we shall specially consider the intercellular fluid and 

 its constituents on the one side, and the blood-cell and its contents 

 on the other, each independently of the other. Hence, in order to 

 make the comparison as plain as possible, we shall give in parallel 

 columns the quantitative relations of these two great factors in the 

 composition of the blood. 



