388 THE BLOOD, BY ALEXANDER ROLLETT. 



they remain extended, and do not undergo any remarkable 

 change in the dimensions of their larger diameter. Welcker* 

 and others have corroborated this statement. The clear spot 

 of the non-nucleated corpuscles, to which alone the above 

 statement is strictly applicable, comes, under these circum- 

 stances, very distinctly into view, but passes without sharp 

 definition into the surrounding darker parts. 



The nucleated corpuscles do not remain quite unaltered 

 in the dimensions of their surfaces ; the variation is, however, 

 of small amount. Many retain their form and smoothness ; 

 others become curved or sinuous. The clear spot correspond- 

 ing to the nucleus, and its delicate markings, come more 

 distinctly into view. In some corpuscles the nucleus, after 

 drying, always appears very sharply defined, and separated 

 from the remaining substance of the blood corpuscles by a clear 

 reddish refractile border investing it like a wall, and making it 

 appear as if lying in a cavity. In blood dried in masses the 

 blood corpuscles are found to present manifold changes of form 

 and to become ultimately attached to one another, so that it is 

 difficult to recognise them in fragments of dried crust. 



4. In the coagula which originate in the lymph sacs of 

 frogs or salamanders after bleeding, according to Rindfleisch ( 

 and Preyer, { coloured or colourless processes are protruded 

 from the substance of the corpuscles, which are at first smooth, 

 but afterwards resemble a string of pearls. According to Preyer, 

 these can be again withdrawn, or may become completely 

 isolated, or may separate into a few spheroidal masses. Beale 

 saw similar changes occur in the red corpuscles on a slide, in 

 consequence of evaporation (? coagulation) and warming. 



5. In order to observe the effect of electrical discharges || and 

 of induction currents upon the blood corpuscles, the arrangement 

 exhibited in pp. 21, 22, of this manual may be employed, except 



* Loc. cit., p. 261. 



t Experimental Studien itber die Histologie des B lutes. Leipzig, 1863, p. 8. 

 J Virchow's Archiv, Band xxx., p. 417. 

 Quarterly Journal of Microscopical Science, No. 13, 1864. 

 || Rollett, Sitzungsberichte der Wiener Aka lemie, Band xlvi., pp. 92 97 ; 

 Band xlvii. pp. 356390 ; Band 1., pp. 178202. 



