20 DR DAVY'S MISCELLANEOUS OBSERVATIONS ON THE BLOOD. 



On the addition of four of water, the corpuscles were seen less distinctly, yet 

 they were to be seen, the adjustment being as accurate as possible, and using a 

 warm object-glass, a precaution needed to prevent the dimming of the glass (J, th 

 inch power) from the vapour rising from the fluid in such close proximity. 



When more water was added, the only material difference that I am aware of 

 was not in the effect on the corpuscles, but in their wider diffusion, thus in- 

 creasing the difficulty of observing them. To counteract this, a portion of cruor 

 was mixed with water in a tall vessel, stirred occasionally, and after having been 

 some hours left at rest, the greater part of the coloured fluid — coloured by the 

 solution of the colouring matter of the corpuscles — was drawn off. What remained 

 afforded an interesting result. A drop of this fluid under the microscope 

 exhibited much the same appearance as that from the addition of four parts of 

 water ; and on drying at the same temperature, the appearances were also similar 

 but more strongly marked, suggestive of ruptured capsules and the loss of their 

 contents, with the exception, as in that instance, of some of them retaining their 

 nuclei, these more or less altered. Most of the corpuscles, if that term be applicable 

 to their remains, were circular or portions of circles, portions of them having 

 been broken of. Some showed a rent, a few wore elliptical, and with the excep- 

 tion of being wasted, but little altered in appearance. 



The agency of water on the red corpuscles has commonly been attributed to 

 imbibition or endosmosis, to solution of the soluble matter which these cells con- 

 tain, and to exosmosis. The appearances which I have described seem to har- 

 monise well with this view, with the addition of rupture of the cell-wall or 

 capsule, and the occasional exclusion of the neuclei. They accord, too, tolerably 

 with those noticed by Professor Lehmann, in his Physiological Chemistry,* with 

 the exception of two particulars. He states, that when largely diluted, the cor- 

 puscles become invisible under the microscope, which he attributes to their refrac- 

 tive power, after the action of water, differing but little from that of water itself. 

 As already mentioned, when using certain precautions, I have found them, only 

 much less distinct. The other particular relates to their remains. According to 

 him, these are mere shreds, and not empty and more or less broken capsules, as I 

 have found them to be. The subject, it must be admitted, is one in the investiga- 

 tion of which it is not easy to obtain uniform and satisfactory results, there are 

 so many interfering and disturbing circumstances concerned, not omitting the 

 influence of the serum, and especially keeping in mind the powerful attraction 

 the corpuscles have for water, and their hygroscopic properties ; and further, the 

 changes to which they are liable as dead matter, from the influences to which 

 they are exposed. 



As to the last mentioned, I have found that the longer the blood is kept, the 



* Vol. ii. p. 184. 



