206 
DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
observations which had been made by Di Torre, with his rude and smoked lenses, 
in 1761. No one can feel more conscious than I do, how much we owe to Hewson 
for his researches on the corpuscles of the blood : but I think he erred in dismissing 
as valueless the remarks of the Italian observer. 
68. I would add, once more referring to fig. 23, that the arrangement of the con- 
tents of the blood-corpuscle in the human subject, will be seen to coincide, in some 
instances, with its well-known usually biconcave form (pars. 73 to 76). 
69. The form and internal state of the blood-corpuscle found in the adult of certain 
animals, very much resembles that existing only in the foetal life of others. This will 
be obvious on an inspection of the drawings. That such resemblance is referable to 
uniformity in the mode of evolution, results from our whole experience on the re- 
production of cells, as I explain it, and from facts above mentioned, showing that 
blood-corpuscles are generated by a like process ; the difference between the condi- 
tion of these objects in the embryo and in the adult of the same animal, being appa- 
rently referable to a difference in the degree of their development as cells. 
70. An incidental observation may perhaps be mentioned here. The brain in the 
embryo of the Ox, at certain periods, appears to consist almost entirely of objects 
such as those in figs. 59 and 60; which, it will be seen, are composed of discs. 
Before the addition of acetic acid, such objects in many instances are surrounded by 
a halo, which seems to represent the membrane of a minute cell. If the objects now 
mentioned be compared with some of the nuclei of blood-corpuscles which I have 
figured, it will be found that there is a remarkable similarity between them. 
71. On a review of the facts stated in the course of the present communication, 
the opinion I have been led to form, is that the mode of evolution of the minute 
mainmiferous ovum is deserving of close attention in connection with some of the 
processes by which nourishment is communicated, and the growth of the body 
effected at all future periods of life. 
Appendix. 
The following additional remarks were kept out of the memoir itself, for the pur- 
pose of rendering it as simple and brief as possible. 
72. The chemical reagent principally used in the investigations forming the sub- 
ject of this paper, has been dilute acetic acid of the strength of distilled vinegar. I 
have found it an advantage to add this acid in a quantity so very small, as to be 
enabled to witness its gradual effect upon the contents of the blood-corpuscle. It has 
been by this means, in part, that I have discerned the interior of this object to be, to 
my astonishment, so different from that represented by previous observers. 
