340 CYTOLOGICAL METHODS. 



made by adding a little of a concentrated solution of iodine in iodide of 

 potassium to 2 per cent, osmic acid ; and some other formulae useful for 

 their special objects (most various forms of Arthropoda). 



SWAEN ET MASQUELIN (Arch, de BioL, iv, p. 752). Selacians, Sala- 

 mandra, Bos. 



FLEMMING (Arch. f. mik. Anat., xxix, 1887, p. 387 ; abstracts in Zeit. f. 

 wiss. Mik., v, 2, 1888, p. 236, and Journ. Roy. Hie. Soc., 1888, p. 146). 



PBENANT (Intern. Monatschr.f. Anat., iv, 1887, p. 358 ; abstracts in Zeit. 

 f. wiss. Mik., v, 1, 1888, p. 84 ; and Journ. Roy. Mic. Soc., 1888, p. 844 

 [Mammalia] ). 



KENSON (Arch, de BioL, iii, 1882, p. 302). 



BENDA (Arch. f. Anat. u. Phys. ; Phys. Abth., 1886, p. 186). For his 

 modification of Weigert's hsematoxylin stain, see below. 



JENSON (Arch, de BioL, iv, 1883, p. 11, et passim [Selacians and Inverte- 

 brates] ). Concentrated solution of oxalic acid for hardening. 



PICTET (Mitth. a. d. zool. Stat. zu Neapel, Bd. x, Hft. 1, 1891, p. 89). 

 Instructive series of figures showing the very different forms assumed by 

 spermatozoa of Strongylocentrotus under treatment by twenty -three different 

 reagents. The most faithfully-preserving examination fluid was found to 

 be a 5 to 10 per cent, solution of chloride of manganese containing a small 

 quantity of dahlia dissolved in sea water. 



For some reactions of divers stains on the nucleus and Nebenkem of 

 spermatozoa, see LECLERCQ, Bull. Acad. Roy. Belg., Ix, 1890, p. 138; 

 Journ. Roy. Mic. Soc., 1890, p. 816. 



BALBIANI (Leg. sur la Gener. des Vertebres, 1879, p. 244). Double-stain 

 sections with picro-carmine and methyl green. The latter stages of differ- 

 entiating cells stain blue, less advanced ones lilac ; and the cells which form 

 the walls of the tubes stain only red. 



KYDEE, in WHITMAN'S Meth. of Research, p. 52. Sections of hermaphro- 

 dite gland of Lamellibranchiata stained for two or three hours in a mixture 

 of equal parts of concentrated alcoholic solution of safranin and methyl 

 green, diluted with 8 volumes of water, washed out for five to ten minutes 

 in alcohol, and mounted in balsam. Nuclei of ova, red ; heads of sperma- 

 tozoa, bluish green. 



If sections of a gland of Helix be stained with methyl green and eosin, 

 the ova are stained rose colour, and the spermatozoa bluish green (HENNEGUY, 

 in Traite des Meth. Techn., LEE et HENNEGUY, p. 343). 



AUEBBACH (Sitzb. k. Acad. Wiss. Berlin, xxxv, 1891, p. 713 ; see Journ. 

 Roy. Mic. Soc., 1891, p. 714 ; Zeit.f. wiss. Mik., ix, 1, 1892, p. 81) has made 

 some observations which seem to point to a qualitative chemical difference in 

 the composition of the nuclei of male and female sexual products. Sections 

 of male and female sexual products, prepared in precisely the same way, 

 were fixed together on slides and stained with pairs of the following dyes 

 (used either mixed or in succession) : 



