22 Addison, on Blood-corpuscles. 



line and saline fluids, are like forms d, fig. 3, which are pro- 

 duced in acid liquids, the only difference between them being 

 that those observed in alkaline are deeper coloured than those 

 in acid fluids. Corpuscles of this form b, fig. 2, and d, 

 fig. 3, are incapable of regaining the normal form. Ulti- 

 mately, in alkaline fluids, the forms b, fig. 2, burst open, 

 and the corpuscles are wholly dissolved; in acid liquids 

 (fig. 3, d) they sometimes burst open suddenly, and some- 

 times suddenly increase in size, the contents of the corpus- 

 cles become colourless, and the enlarged capsules, with a 

 granular matter within them, have very much the appearance 

 of the white corpuscles of the blood (fig. 3, e) . 



Dissolve a grain of common salt and half a grain of bicar- 

 bonate of soda in two fluid drachms of water, mix this 

 solution with half a fluid ounce of good sherry wine, and 

 filter. This liquid produces the tailed corpuscles (fig. 4). A 

 small drop of blood and an equal quantity of the vino-saline 

 mixture must be placed side by side on a slip of glass, so that 

 their edges may mingle when a thin covering-glass is dropped 

 upon them. In about five or ten minutes numerous corpus- 

 cles, where they have floated out in the liquid, will be seen 

 throwing out matter from their interior, two, three, four, 

 or more minute molecular particles fringing their circum- 

 ference. Some of these molecules separate from the cor- 

 puscles and float in the fluid, others elongate into tails, which 

 wave about with a tremulous motion, in a very remarkable 

 manner. These tails all have a little knob at then* extremity. 

 After a short time, or upon any motion in the fluid, the tails 

 break away from the corpuscles, but their singular move- 

 ments do not cease when this has happened. Sometimes a 

 discoid enlargement forms on some part of the tail, and then 

 the tail suddenly retracts itself into a larger granular and 

 coloured particle. That the movements of these tails are of 

 a peculiar kind, and not due to motion in the liquid, is shown 

 by this — that all movement in them ceases entirely when 

 they approach near to either of the edges of the covering, 

 thin glass. In repeating this experiment, if the surfaces of 

 the upper and under glasses come so close together as to 

 press upon the blood-corpuscles — which is known by increase 

 of their diameter — the tails will not appear. The corpuscles 

 must be free from pressure, for the effects described to take 

 place. Moreover, tails are not readily produced if the 

 stand of the microscope and the glasses are cold ; the phe- 

 nomenon takes place much sooner, and the tails are longer, 

 when the instrument and fluids have been for some time in a 

 warm room. 



