74 On a Possible Explanation of the Method emjoloyed by Nobert 
E. Briicke already has said of other protoplasm bodies), must 
become a recognized one. 
I cannot explain the representations, of which one is given in 
Fig. 6, in any other way than by saying thus : The first-formed 
blood- corpuscles, the hamatoblasts, are without nuclei, and the 
ready-formed blood-corpuscles alone have any. We cannot search 
for the sources of the blood formation in mammals without regard- 
ing the nucleus as a postulate (ein postulat) of the stage of youth. 
Whilst I regard as certain the new formation of red blood- 
corpuscles out of the hamatoblasts on the ossification border of 
the hyaline cartilage in growing birds, I must, on the other 
hand, observe that this new formation does not take place in full- 
grown animals. 
Even in a nine-months' old pigeon, ready-formed bone tissue, 
with flat tissue containing medullary spaces, joins immediately a 
layer of round cartilage corpuscles, which show no cartilage marrow- 
spaces. The blood-vessels of these marrow-spaces form loops at 
the upper (towards the cartilage turned) ends. The intermediate 
stage of the lime deposit of the elementary substance, as well as 
any representations which might signify a new formation of blood- 
vessels and hamatoblasts, are wanting here. In still older animals, 
where the layer of hyaline cartilage appeared still more reduced, 
the upper ends of the marrow-spaces were isolated from the car- 
tilage by means of lamellated layers of bone tissue. — Max Schultzes 
Archiv, Band xii. 
lY. — On a Possible Explanation of the Method employed by 
Nobert in Ruling his Test-Plates. By William A. Kogers. 
I RECOGNIZE the fact that no explanation of a purely mechanical 
process can be regarded as either satisfactory or final, which does 
not answer the crucial test of reproduction. I offer to the 
reader what I believe may prove to be an explanation of the 
process followed by Nobert in ruling his test-plates ; the highest 
band which has been resolved under the microscope, reaching 
112,600 lines to the inch. You properly ask me if I can reproduce 
these rulings. I frankly answer that I cannot. Indeed, I can hardly 
hope ever to succeed in producing lines which combine the wonderful 
delicacy, uniformity, and distinctness found in nearly all of Nobert's 
plates. But I have reached what I hope may prove to be a useful 
approximation to Nobert's results. Beginning with 2000 lines to 
the inch in 1871, I have now little difficulty in reaching 60,000, 
the width of each line being a little less than one-half of the inter- 
vening space. Several of my plates have been correctly counted as 
