

DEVELOPMENT OF THE BLOOD CORPUSCLES. 



description of the intermediate forms that may be observed. 

 Sclarewsky* and Golubewf have also been lately occupied with 

 the investigation of the intermediate forms between the white 

 and red blood corpuscles. From the statement of these authors 

 it is to be concluded that the pale cells, which otherwise resemble 

 red blood corpuscles, occurring in the blood of the Frog, and 

 described by earlier observers, are to be regarded as amongst 

 these intermediate forms. 



From the facts just mentioned, we are directly conducted to 

 the difficult questions of the origin and regeneration of the 

 organised constituents of the blood. 



DEVELOPMENT OF THE BLOOD CORPUSCLES. 



The first coloured blood corpuscles in the fowl originate con- 

 temporaneously with the formation of the first vessels in the 

 germinal area, or in the vascular area and area opaca,\\ and 

 they either detach themselves from the walls of the vascular 

 spaces (Afanasieff), hanging together in isolated groups (blood 

 islands, Wolf and Pander), or they may originate, according to 

 the view of His, in the form of groups, from large masses of 

 protoplasm in the walls of the vessels, and at a later period 

 burst into their lumen. Soon after the coalescence of the vessels 

 with the heart, these primordial blood corpuscles, which are 

 lying ready to be borne onwards by the current, are floated off 

 either separately or in groups (His). The primordial blood 

 cells exhibit numerous processes and outgrowths (His). More- 

 over, the coloured blood corpuscles circulating during the later 

 periods of intra-oval life exhibit numerous forms attributable 

 to fission, which have been described and depicted by Remak.H 



* CentralUatt fur die medicin. Wissenschaften, 1867, p. 865. 



t Loc. cit., p. 566. 



f Wharton Jones, Philosophical Transactions, 1846. Hensen, loc. cit. t 

 p. 263. 



Afanasieff, Sitzungsberichte der Wiener Akademie, Band liii., p. 560. 



|| His, Untersuchungen uber die erste Anlage des Wirbelthierleibes. 

 Leipzig, 1868, p. 95. 



1[ Untersuchungen uber die Entwickelung der Wirbelthiere, Berlin, 1855. 

 p. 164 ; Miiller's Archiv, 1858, p. 178. 



