Ossification Process in Birds, &c. By Br, L. Schdney. 71 
offspring of the marrow elements, and as the real bone-forming 
element. He still adhered, it is true, to the secretion theory, because 
it might be considered the most simple one. Herr Waldeyer pro- 
nounced for the direct transformation of one part of the osteoblast 
into elementary bone structure in Max Schultze's sense ; and lastly, 
C. Heitzmann observed that during the transformation of the 
osteoblasta in bony elementary substance, the living matter in the 
interior of the same was preserved, whilst the protoplasm liquid 
only, changed into a gelatin-giving one. 
Fig. 5 illustrates the process with an almost diagramatic 
clearness. This drawing is taken at the spot where direct new- 
formed bone joins the limeless cartilage. We see limeless cartilage 
(a), then a hyaline zone (h) . This zone joins the bone elementary 
substance (c) with a sprinkling of the characteristic bone-corpuscles ; 
and lastly, we see a layer of osteoblasts (d). On the border between 
0 and D are seen all the transitions of free (not infiltrated) osteo- 
blasts into those which disappear in elementary substance. The 
tender granulation of the newly-formed osteogenous substance, 
however, indicates that the structure of the osteoblasts did at least 
not entirely disappear during the formation process of the bone. 
I can therefore confirm the view that the flat protoplasm bodies, 
which Gegenbaur called osteoblasts, are real bone-formers ; I also 
have seen that the osteoblasts are connected among one another by 
delicate threads (Gegenbaur's thorns). Equally must I maintain 
the transformation of one part of the osteoblasts into bone elemen- 
tary substance in Waldeyer's meaning. But I am not prepared to 
assert that in the bones of birds the osteogenous elementary 
substance contains living matter ; I only am bound to observe that 
the bone of birds is constructed exactly as in mammals, as I have 
been taught, by longitudinal and transverse sections through femur 
and tibia. 
Here too we find lamina systems arranged round the vascular 
canals ; here too we find in the cavities of the elementary substance 
protoplasmic bodies which are described as bone - cells ; here too 
we find the well-known star-like projections. But how far the 
bone, as regards contents of hving matter, accords with that of the 
mammals, future researches alone will show. 
II. New Formation of Blood and Blood-vessels, 
I have studied the new formation of blood with special care. 
E. Neumann* has denied the theory of the blood formation as 
regards the new formation of red blood-corpuscles on the ossification 
border of the cartilage. At the same time he drew attention to 
* Heitzmann's " Hamatoblasten," ' Archiv fiir mikros. Anatomit ,' Nov. 1874. 
