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XVIII. Observations on the Blood Corpuscles, or Eed Particles, 

 of tlxe Mammiferons Animals. By George Gulliver, 

 F.R.S., Assistant Surgeon to the Royal Regiment of Horse 

 Guards. No. II.* 



IN my formei' 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 beof 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 thickl}' 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 by 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 are^not worthy of much reliance. The shrinking, 



* Communicated by the Author, f L, & E. Phil. Mag. for January 1840. 



