402 THE BLOOD, BY ALEXANDER ROLLETT. 



alkalies can, according to Addison, be changed by acid solu- 

 tions into the form they induce, and vice versa. 



g. Urea,* in the state of fine powder, or in solution in water, 

 in the proportion of from twenty-five to thirty grammes or less 

 in 100 cubic centimeters of water, powerfully affects the form of 

 the corpuscles, though they are not all affected in the same way. 

 In the blood of Amphibia some of the corpuscles always 

 assume a curved form, and then small drops and spherical 

 fragments become detached from them. Others become spheri- 

 cal without undergoing any further alteration in shape ; but 

 both large and small spheroids ultimately become colourless. 

 During the assumption of the spheroidal form some of the 

 corpuscles discharge their nuclei. The latter become slightly 

 enlarged in the Frog, but much augmented in volume in the 

 Triton, and then assume the remarkable appearance of a 

 trabecular framework with large meshes. The nuclei which 

 do not escape undergo similar changes if once the spheroid 

 become colourless, so that the pale clear remains of the sub- 

 stance of the blood corpuscles appear as a kind of appendage 

 to the enlarged nucleus. To regard these structures as 

 nucleated albuminous spheroids escaped from adjoining coloured 

 corpuscles is due to a misconception of the phenomena 

 observed.f 



If we now consider the action of less concentrated solutions 

 of urea, we find that the incurvation of the corpuscles and 

 detachment of drops is of rarer occurrence, and that the 

 majority of corpuscles immediately become spherical, and at a 

 subsequent period, together with the nucleus, entirely vanish. 

 The incurvation of the border and the formation of drops is 

 also exhibited by the non-nucleated blood corpuscles of Mam- 

 mals when treated with urea. 



h. Neutral solutions of carmine in pure ammonia (one gramme 

 of carmine in 200 cubic centimeters of solution) produce on the 



* Hiihnefeldt, Chemismus in der thier. Natur., 1840, p. 60. Kolliker, 

 Zeitschrift fur wissenschaftliche Zoologie, Band vii., pp. 184, 253. Botkin 

 Virchow's Archiv, Bandxx., p. 37. Heusen, loc. cit., p. 264. Vintschgau' 

 loc. cit., p. 13. Preyer, loc. cit., p. 432. Kneuttinger, loc. cit., p. 56. 



t Kneuttinger, loc. cit., p. 58, fig. 9 b. 



