1894.] MICROSCOPICAL JOURNAL. 365 



ished some studies of the area vasculosi of the embryo of 

 the chicken. 



HcBmatohlasts are granules or isolated lumps of living 

 matter not yet of the size of red blood corpuscles. They 

 are early forms of red blood corpuscles and develops into 

 such. They are homogenous if s?nall, the size of granules 

 say 1.5 micro millimeters and the more distinctly reticular 

 in structure the nearer they reach the size of red blood cor- 

 puscles. They are from the very beginning saturated toith 

 haemoglobin. 



Most writers quote Hayem as the discoverer of these 

 bodies which is erroneous, for neither the name haema- 

 toblast nor an accurate description of them can be credi- 

 ted to him. Foster's Medical Dictionary is, as far as I 

 know, the only work mentioning C. Heitzmann as the 

 originator of the name. (See article Haematoblast in 

 this work.) This author defines a haematoblast correctly 

 when he says they are miniature red blood corpuscles. 

 This term is applied also to small, colorless, circular or 

 ovoid bodies, 1-2 to 1-6 the size of red blood corpuscles 

 circulating in the blood of mammals. It is, according to 

 Foster, probably identical with the Haematoblast of 

 Hayem and the blood plate of Osier. This is an er- 

 ror, the same one Hayem himself made when describing 

 the hsBmetoblasts in 18V7. 



Heitzmann ("Studien am Knochen und Knorpel, Jalir- 

 biicher, 1872,) described the changes occuring in the 

 hyaline cartilage preceeding the formation of bone tissue. 

 At the border of the hyaline cartilage may be found 

 isolated lumps of living matter with high refraction, of 

 a yellowish color, evidently arising from previous cartil- 

 age corpuscles. He says " as the shining solid corpus- 

 cles exhibited stages of development advanced to the 

 formation of nearly perfect red blood corpuscles, I con- 

 sidered them to be juvenile forms of the latter and pro- 

 pose for their designation the term hcematoblast. I con- 



