206 DR. xMARTIN 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 7^)' 



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 

 mammiferous 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. 



