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XVIII. Obsermtions on the Blood Corpuscles^ or Red Particles^ 
of the Mammiferous Animals, By George Gulliver, 
F.R,S., Assistant Surgeon to the Royal Regiment of Horse 
Guards, No. II.^ 
I N my former cornmunicationf I omitted to mention that 
in many of the observations an achromatic object glass was 
used, of one tenth of an inch focal length, made by Powell, 
and adapted to the same eye-piece as the excellent object-glass 
by Ross. They both perform admirably, and the additional 
power gained by the former one is not only of considerable 
advantage, but it affords an opportunity of instituting com- 
parative trials, so as to diminish the chances of error. Both 
these glasses will therefore be employed in the succeeding 
observations, and I shall avail myself of opportunities of test- 
ing the measurements previously given, and of recording the 
results when they seem to be of any consequence. The mag- 
nifying power of Powell’s glass with the micrometer eye-piece 
is as nearly as possible nine hundred and eighty diameters, 
and the object is very distinctly defined. 
After repeating very carefully numerous observations on 
the corpuscles in their own serum, as compared with speci- 
mens dried in the manner formerly described, it appears that 
the latter are almost always a little larger and more accurately 
defined in the outline than the former. This is particularly 
observable at the margins of the dried preparations, where 
the corpuscles are very thinly spread, and where desiccation 
takes place instantaneously when they are applied warm from 
the wound to the glass. Towards the centre, as the particles 
are more thickly aggregated, they do not dry so quickly, but 
have time to contract a little, and accordingly correspond in 
diameter pretty accurately with those observed in their own 
serum. I have noted instances in which they manifestly 
shrunk while under examination in the serum, as if they were 
acted on b}^ the glasses between which they were placed, the 
edges of the disks becoming more rounded, occasionally gra- 
nulated, and not unfrequently puckered or swollen, so that 
the central concavity in many of them was very remarkable, 
and often more or less misshapen from the bulging of the 
edges towards the centre, a triangular depression with con- 
cavity of the margins being thus occasionally produced on the 
surface of the corpuscles. 
Though saline solutions are useful in diluting the blood for 
comparative observations, measurements from corpuscles so 
preserved arehiot worthy of much reliance. The shrinking, 
* Comirmnicated by the Author, f b. & E. Phil, Mag. for January 1840. 
