PROPERTIES OF COLOURLESS BLOOD-CORPUSCLES. 183 



different qualities of blood. But in opposition to such 

 an idea it must be remarked, that, although in the cases 

 in which the one or the other kind of corpuscles exist in 

 large quantities, we have to deal with a pathological phe- 

 nomenon, yet that, when we do not find such large 

 quantities, we have before us only an earlier or a later 

 stage of the development of the elements. For one and 

 the same blood-corpuscle may, in the course of its life, 

 have one or several nuclei, the one belonging to an 

 earlier, the several to a later, stage of its existence. 

 You must always bear in mind, that the change is seen 

 to take place in the same individual in a short time, in- 

 deed often in the course of a few hours, so that in blood 

 which had previously only contained one sort, after- 

 wards quite a different one may be found a proof of the 

 rapidity of the change to which these bodies are sub- 

 jected. 



Allow me, gentlemen, to add a few words with regard 

 to the more palpable relations which the individual con- 

 stituents of the blood present towards one another. It 

 is, as you well know, generally assumed that of the mor- 

 phological constituents only two are accessible to the 

 grosser perception of the naked eye, namely, the red 

 corpuscles in the clot, and the masses of fibrine, which 

 under certain circumstances form a buffy coat, but that, 

 on the other hand, the colourless cells are not to be per- 

 ceived by the unaided sight. This is a notion which I 

 consider myself bound to correct. The colourless cor- 

 puscles, whenever they are present in considerable num- 

 bers, become very distinctly manifest to the more prac- 

 tised eye during the separation of the constituents of the 

 blood, and especially when the coagulation is accompanied 

 by movement ; and they then exhibit a peculiarity, 

 with which it is as well that one should be acquainted 

 when one is required to pass judgment upon specimens de- 



