24 Mr. G. Gulliver’s Ohservation$ on the Blood Corpuscles 
propose to give an account of the blood corpuscles of such 
animals as I have had an opportunity of examining. Of many 
of these particles 1 believe no description has hitherto been 
published ; and some others which have been previously de- 
scribed I have examined anew with a view to more accurate 
comparisons. I am not aware that the peculiar form of the 
corpuscles in certain species of the genus Cerms has been 
hitherto observed in any class of animals. 
The general results appear interesting to me in many points 
of view, particularly in respect to certain differences in the 
size of the corpuscles in the same individual at different pe- 
riods of existence, as well as in nearly allied species of the 
same genus ; and the resemblance, on the other hand, of the 
blood disks in some groups of the animal kingdom. The 
connexion, too, between the size and form of the blood par- 
ticles and the respiratory organs, I have found to be remarkable. 
But before entering into conclusions it will be necessary to give 
the observations in detail, reserving a summary arrangement 
of them, and the deductions which they appear to warrant, for 
a future section of this memoir, when an opportunity will be 
afforded of reference to the labours of others in this field. 
The instrument made use of in these observations is a com- 
pound microscope, with an achromatic object-glass of one- 
eighth of an inch focal length, made by Ross, and furnished 
by him with a micrometer eye-piece divided into spaces cor- 
responding to 1 -4000th of an inch. The magnifying power 
afforded is exactly 800 diameters with a clear definition. 
If one space and a quarter of this micrometer were occu- 
pied by a single globule, this would of course measure l-3200th 
of an inch ; if three equally-sized particles lying in a line, 
and touching at their edges, covered three spaces and a half, the 
diameter of each of these would be l-v3429th, — if four spaces, 
l-v3000th of an inch. Now these measurements are mentioned 
because they are very frequently obtained from the average- 
sized human blood disks, which are to be distinguished from 
the remarkable varieties which Mr. Bowerbank has observed 
among them, and which I have also witnessed, though I think 
in a less degree than he mentions, in man and various ani- 
mals. In the human blood corpuscle, the diameter last 
mentioned is not so common as the two former. In the ab- 
solute accuracy of any micrometer applied to objects so ex- 
tremely minute, it is difficult to place implicit reliance ; but 
avoid acknowledging the kindness and urbanity’ of Mr. Ogilby, W'ho enter- 
tained iny application with his usual zeal in the promotion of zoological 
inquiries. I have also repeatedly been indebted to the kind assistance 
of Mr. Youatt, the excellent medical superintendent of the Gardens. 
