"iSS.sSr^^^^^^^ Corpuscles in Blood-stains, 151 
blood corpuscle surrounded by rouleaux of red ones, water was in- 
troduced at the edge of the cover by means of a thread from the 
reservoir. As the wave of fluid, deeply tinged with colouring 
matter it had dissolved, crossed the field of the microscope, the cor- 
puscles were, for a few moments, obscured, but in a short time the 
white cell reappeared, and soon after the very faint but unmis- 
takable outlines of the red discs again became visible. This experi- 
ment was varied by irrigating some fields exhibiting isolated red 
corpuscles, and others where by crowding together they had 
formed an apparently homogeneous clot, in every case with the 
same result where a high power was employed ; with the J-inch 
objective, however, I was unable to satisfy myself of the existence of 
these eviscerated discs. By careful measurement with the cobweb 
micrometer, the white corpuscles were found to first diminish 
slightly on contact with water, and afterwards to expand to rather 
more than their original diameter, while the red discs appeared to 
sufier a permanent decrease from about to ^^Vo^ of an inch 
across. 
Ex]pt. 3. — Some minute fragments of dried blood from a stain 
made upon a piece of muslin about three months before were placed 
upon a slide and adjusted on the stage of the microscope ; after finding 
a suitable portion of clot with a thin bevelled edge, water was intro- 
duced at the margin of the cover and allowed to flow very slowly 
towards the chosen fragment ; when this was reached by the wave 
of fluid a remarkable appearance of boiling up from its centre was 
presented for a few moments, and then as the tinged liquid was re- 
placed by pure water an aggregation of compressed corpuscles, very 
faint and colourless, but yet of unquestionable distinctness, became 
apparent ; a few straight interlaced filaments of fibrin were visible, 
and at intervals the granular spherical lymph globules occurred 
among the other elements; these white cells frequently became 
detached, and floated freely around the edges of the clot, where, 
as well as whilst still embedded, they were so much more readily 
recognized with a low power that I suspect they have often been 
mistaken for the red discs. By introducing at the margin of the 
cover, a minute portion of iodine solution,* the outlines of the de- 
colourized corpuscles are rendered far more obvious, and can often 
be distinguished even by inexperienced observers. 
In a similar manner the blood of an ox, sheep, pig, chicken, 
turkey, and canary bird, most of them dried in a thin film upon a 
slide, and all dried in a mass upon paper or muslin, were carefully 
examined, and little difficulty found in distinctly perceiving that the 
colourless stroma with its " straight or slightly waving filaments, 
sometimes more fibrous, sometimes more wrinkled and homo- 
geneous," f so long mistaken under lower powers for a mass of 
fibrin, was actually an aggregation of decolourized red corpuscles, 
* Bcale, ' How to Work with the Microscope,' p. 207. f Virehow, loc. cit. 
