Cellular Structure of the Red Blood Corpuscle. 17 



considerable number of red globules might bo separated, the deposit 

 on the filter should be dashed with a little water, and this solution 

 either examined by itself, or added to the filtered urine. If the 

 depth of colour in the ten-inch tube be so great, that the yellow end 

 of the green part of the spectrum is absorbed, the urine must be 

 somewhat diluted, or examined in a shorter tube. When the depth 

 of colour is about an average, I find that by this means as little as 

 ro^^o^th part of blood can easily be detected in fresh urine, v\hich is 

 equivalent to about one drop in a pint. 



Y. — On the Cellular Structure of the Bed Blood Corpuscle. 



By Joseph G. Eichardson, M.D., Microscopist to the Pennsylvania 

 Hospital, Philadelphia, Pennsylvania. 



For many years after the magnificent cell theory was first accepted 

 by physiologists, the doctrine of Schwann, who regarded the red 

 blood disks as minute membranous sacs containing a coloured fluid, 

 passed almost unquestioned ; but of late, especially since more care- 

 ful microscopic observations have become customary, it has been 

 found that the supposed bursting of these little bladders, long 

 looked upon as one of the strongest proofs of their cellular nature, 

 does not take place, and at the present time some of our leading 

 authorities, both in America and in Great Britain, assert positively 

 that the coloured blood disks are non-vesicular, and deny any dif- 

 ferentiation of their substance into cell wall and cell contents. 



Thus, for example, Professor Austin Flint, jun., in the second 

 volume of his great work on the 'Physiology of Man,' p. 11(5, 

 remarks : — " The structure of the blood corpuscles is very simple. 

 They are perfectly homogeneous, presenting in their normal condi- 

 tion no nuclei or granules, and are not provided with an investing 

 membrane. A great deal has been said by anatomists concerning 

 the latter point, and many are of the opinion that they are cellular 

 in their structure, being composed of a membrane with viscid semi- 

 fluid contents. Without going fully into a discussion of this point, 

 it may be stated that few have assumed actually to demonstrate 

 this membrane, but they have for the most part inferred its exist- 

 ence from the fact of the swelling, and, as they term it, bursting on 

 the addition of water ; and particularly, as it seems to me, to make 

 the blood corpuscles obey the theoretical laws of cell development 

 and nutrition laid down by Schwann. Their great elasticity, the 

 persistence with which they preserve their bi-concave form, and 

 their general appearance, would rather favour the idea that they 

 are homogeneous bodies of a definite shape, than that they have 



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