104 



ORIGIN OF COLORED BLOOD-CORPUSCLES. 



" On watching specimens from the border of ossification of a 

 growing chicken, we see within melted portions of the calcified 

 basis-substance, homogeneous, shining lumps, in club-shaped 

 spaces, inclosed by spindle-shaped elements. These spaces are 

 not connected with perfect blood-vessels. The authors agree in 

 considering such club-shaped formations as the first appearance 

 of blood-vessels in the center of a medullary space. What are 

 the shining corpuscles in the interior of a future vessel ? What 



else than not fully de- 

 veloped blood - corpus- 

 cles ? therefore, hae- 

 matoblasts. It is re- 

 markable that these 

 corpuscles have no nu- 

 clei, and corpuscles 

 crowded in blood-ves- 

 sels toward the bone- 

 tissue, the connection 

 of which with older 

 blood-vessels is not yet 

 evident, also want nu- 

 clei. Nucleated blood- 

 corpuscles, so charac- 

 teristic in birds, are 

 visible only in deeper 

 layers of the fully 

 formed bone-tissue. If 

 we admit that the 

 youngest medullary 

 formations are found 

 in the ossifying borders 

 of the cartilage, and 

 that in the medullary 

 spaces there are pres- 

 ent corpuscles, to be considered as blood-corpuscles, we may 

 readily accept the possibility that the nucleus is not an early, 

 but rather a later, formation. This would agree with the state- 

 ment of E. Briicke, concerning the formation of the nucleus in 

 different other protoplasmic bodies. (See Fig. 30.) 



" The specimen illustrated above admits of but one interpreta- 

 tion, viz. : that in fowls the first formed blood-corpuscles, the 

 haematoblasts, have no nuclei; whereas complete red blood- 



FIG. 30. OBLIQUE SECTION THROUGH THE 

 BORDER OF OSSIFICATION OF THE CONDYLE 

 OF FEMUR OF A YOUNG CHICKEN. 



The central medullary space is surrounded by the 

 calcined frame, C, of the hyaline cartilage, and in its mid- 

 dle there are several club-shaped spaces containing 

 hsematoblasts, H. In the lowest space, B, the red blood- 

 corpuscles do not yet exhibit nuclei. Magnif. 700 diam. 



