BLOOD- GLOBULES. 



221 



Fig. 61. 



broken up as the action of the acetic acid upon the globule is 

 longer continued. (Fig. 61.) This collection of granular matter 

 often assumes a curved or crescentic form, as at a, and sometimes 

 various other irregular shapes. It does not indicate the existence 

 of a nucleus in the white globule, but it is merely an appearance 

 produced by the coagulating 

 and disintegrating action of 

 acetic acid upon the substance 

 of which it is composed. 



The chemical constitution 

 of the white globules, as 

 distinguished from the red, 

 has never been determined ; 

 owing to the small quantity 

 in which they occur, and the 

 difficulty of separating them 

 from the others for purposes 

 of analysis. 



The two kinds of blood- 

 globules, white and red, are 

 to be regarded as distinct 

 and independent anatomical 

 forms. It has been sometimes supposed that the white globules 

 were converted, by a gradual transformation, into the red. There 

 is, however, no direct evidence of this ; as the transformation has 

 never been seen to take pla%e, either in the human subject or in 

 the mammalia, nor even its intermediate stages satisfactorily ob- 

 served. When, therefore, in default of any such direct evidence, 

 we are reduced to the surmise which has been adopted by some 

 authors, viz., that the change " takes place too rapidly to be de- 

 tected by our means of observation," 1 it must be acknowledged 

 that the above opinion has no solid foundation. It has been stated 

 by some authors (Kolliker, Gerlach) that in the blood of the 

 batrachian reptiles there are to be seen certain bodies intermediate 

 in appearance between the white and the red globules, and which 

 represent different stages of transition from one form to the other ; 

 but this is not a fact which is generally acknowledged. We have 

 repeatedly examined, with reference to this point, the fresh blood 

 of the frog, as well as that of the menobranchus, in which the large 



WHITK GLOBULES OF THE BLOOD; altered by 

 dilute acetic acid. 



Kolliker, Handbuch der Gewebelehre, Leipzig, 1652, p. 582. 



