426 SOME OTHER HTSTOLOGtCAL METHODS. 



case. " Plut ist ein ganz lesonderer Soft" * and will not 

 yield up its secrets to such simple wooing. The technique of 

 blood is most elaborate ; see, for instance, the voluminous 

 work of HAYEM, Du sang et de ses alterations anatomiques, pp. 

 1035, with 126 figures, Paris, Masson, 1889 (a report of over 

 twenty pages on this important work is contained in Zeit. f. 

 wiss. Mik., vi, 3, 1889, p. 330, et seq.) ; LOWIT, Sitzb. k. Acad. 

 Wiss.Wien,3, Ixxxviii, 1883; xcii, 1885; xcv, 1887; Zieg- 

 ler's Beitr. z. path. Anat., x, 1891, p. 214; Zeit. f. wiss. Mik., 

 vi, 1889, pp. 74, 76; viii, 3, 1891, p. 371; Arch. f. mik. Anat., 

 xxxviii, 1891, p. 524; Zeit. f. wiss. Mik., ix, 2, 1892, p. 233; 

 Studien zur Physiol. u. Path. d. Blutes u. d. Lymphe, Jena, 

 Fischer, 1892; EHRLICH, Zeit. f. klin. Medicin, i, 1880, 3, 

 p. 558; Zeit.f. wiss. Mik., i, 1884, p. 382, and other papers; 

 MUELLER, Sitzb. k. Acad. Wiss. Wien, xcviii, 3, p. 219; Zeit. 

 f. wiss. Mik., ix, 3, 1893, p. 365 ; GRIESBACH, Zeit.f. wiss. Mik., 

 vii, 3, 1890, p. 326 ; and many other investigators. 



It is out of the question for me to attempt to abstract these 

 memoirs in the space at my disposal, so I must confine myself 

 to giving a few methods that may be useful to the general 

 student, referring the specialist to the original papers. 



803. Fixing and Preserving Methods. The time-honoured 

 process of drying drops of blood over a flame gives rise to 

 great deformation of the elements, and should be abandoned 

 as far as possible. It is better to mix the blood at once 

 with some fixing and preserving medium, and study it as a 

 fluid mount. 



Most recent authors (BiONDi, Mosso, MAX FLESCH) are 

 agreed that by far the most faithful fixing agent for blood- 

 corpuscles is osmic acid. A drop or two of blood (Biondi re- 

 commends two drops exactly) is mixed with 5 c.c. of osmic 

 acid solution, and allowed to remain in it for from one to 

 twenty-four hours. The exact degree of concentration of the 

 osmium solution is a somewhat important point, and must be 

 made out by experiment for each form. As a rule it should 

 be strong, 1 to 2 per cent. According to Biondi, 2 per cent. 

 is best. Fixed specimens may be preserved for use in acetate 

 of potash solution (MAX FLESCH, Zeit. f. wiss. Mik.,v, 1, 1888, 

 p. 83). 



* Goethe's Faust, i, 4, line 1387. 



