THE BLOOD. 79 



is there the slightest danger of confounding them with the 

 white corpuscles, which are also to be seen retaining their 

 uniformly molecular aspect. 



The corpuscles just described exist not merely in the blood 

 of the adult fowl, but they may be detected, with similar 

 facility, in every Oviparous Vertebrate animal the blood of 

 which I have examined ; and they abound in the blood of 

 tritons and frogs. (Plate IX. fig. 5.) 



But further there may be detected in the blood of adult 

 Oviparous Vertebrata, not merely the delicate and pale cor- 

 puscles referred to, but also numbers of naked nuclei, that 

 is, of nuclei deprived of all trace of investing membrane. 

 (See Plate IX. figs. 3 and 5.) 



These nuclei should, however, be examined with care, and 

 a nice adjustment of the object-glass ; for it will be found, on 

 close examination, that many of them, though appearing at 

 first sight to be naked, are not really so, but are invested by 

 a scarcely perceptible envelope. 



Now these large and slightly coloured oval corpuscles, the 

 smaller perfectly colourless and mostly spherical ones, and 

 the naked nuclei, represent progressive states of the dissolu- 

 tion of the red blood disc. 



When first I noticed these pale corpuscles and nuclei, I 

 was disposed to think that they represented stages in the 

 upward development of the red blood disc : this opinion was, 

 however, dispelled, by observing that the pale and colourless 

 corpuscles often exceeded greatly in size the smaller true and 

 coloured blood corpuscles. 



There is one circumstance connected with these pale cor- 

 puscles which does not appear to admit of any very satisfac- 

 tory explanation, viz. their occurrence on the field of the 

 microscope in groups. 



A word or two as to the seat or locality in which the work 

 of development of blood corpuscles, and subsequent dissolu- 

 tion of them, is conducted. Physiologists appear always to 

 have been on the look-out for some organ of the body, the 

 especial purpose of which in the animal economy they con- 



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