CORPUSCLES 21 



treated, when viewed in mass by transmitted light, is seen to have lost 

 its opaque appearance and to have acquired a transparent laky tint. 

 Such lake-coloured blood may also be produced by various other means, 

 such as the action of heat (60° C), the alternate freezing and thawing 

 of a portion of blood, and the passage of electric shocks : the change 

 in colour and translucency obviously depends upon the fact that the 

 corpuscles, when deprived of their coloured part, interfere less with the 

 transmission of light than before : such blood is often exceedingly prone 

 to yield crystals of haemoglobin (to be afterwards described). The 

 action of tannin is peculiar fi-om the fact that under certain conditions 

 the coloured part, instead of being diflFused in the fluid, becomes 

 collected into a minute, highly refracting, globular mass which remains 

 attached to the exterior of the stroma (W. Eoberts).* 



The corpuscles alter their shape on the shghtest pressure, as is 

 beautifully seen while they move within the vessels ; they are also 

 •elastic, for they readily recover their original form again. It must be 

 remarked that the blood -corpuscles when viewed singly appear very 

 faintly coloured, and it is only when collected in considerable quantity 

 that they produce a strong deep red. 



The human-blood corpuscles, as well as those of the lower animals, 

 often present deviations from the natural shape, which are most 

 probably due to causes acting after the blood has been drawn fi-om the 

 vessels, but in some instances depend upon abnormal conditions 

 previously existing in the blood. Thus, it is not unusual for many of 

 them to appear indented or jagged at the margin, when exposed under 

 the microscope, (fig. 10, c, c) and the number of corpuscles so altered often 

 appears to increase during the time of observation. This is, perhaps, 

 the most common change ; it occurs whenever the density of the plasma 

 is increased by the addition of a neutral salt, and is one of the first 

 effects of the passage of an electric shock. The corpuscles may become 

 distorted in various other ways, and corrugated on the surface ; not 

 unfrequently one of their concave sides is bent out, and they acquire a 

 cup-like figure. 



Gulliver made the curious discovery Fig. il. 



that the corpuscles of the Mexican deer 

 and some allied species present very 

 singular forms, doubtless in consequence 

 of exposure ; the figures they assume 

 are various, but most of them become 

 lengthened and pointed at the ends, 

 and then often slightly bent, not unlike 

 caraway-seeds. 



The red disks, when blood is drawn 

 fi-om the vessels, sink in the plasma; 

 they have a singular tendency to run p^g h.-Red Corpuscles col- 

 together, and to cohere by their broad sur- lected into Rolls (after Henle). 

 faces, so as to form by their aggregation 



cylindrical columns, like piles or rouleaus of money, and the rolls or piles 

 themselves join together into an irregular network (figs. 10 and 11). 

 (xenerally the corpuscles separate on a slight impulse, and they 



* Proceedings of the Royal Society, vol. xii. p. 481. For some interesting obserra- 

 tions by Dr. W. Addison, F.R.S., on tbe curious eifects produced on red blood-corpuscles 

 by immersion in slierry-wine, see Proceedings of the Royal Society, Dec. 8, 1859. 



