SPERMATOLOGICAL METHODS. 289 



Other Ova. 



HEBTWIG, 0. (Morph. Jahrb., x, 1884, p 338, Rana). 



HEBTWIG, 0. and R. (Jen. Zeit.f. Naturw., xix, 1885, p. 124). Fecundation 

 of Strongylocentrotus (Echinodermata). Careful study of cell-anaesthetics. 

 Abstracts in Zeit.f. wiss. Mik., iii, 4, 1886, p. 505, and Journ. Roy. Mic. 

 Soc., 1887, p. 835. 



612. Spermatological Methods. One of the great difficulties here 

 met with consists in getting a sufficiently rapid fixation of spermatids and 

 spermatozoa, some of which are probably the most rapidly contracting ele- 

 ments that exist. For fresh material, teased on the slide, strong solution of 

 permanganate of potash is very useful, being the most rapidly fixing agent 

 that I know of. Tincture of iodine is also useful. For staining, gentian 

 violet or dahlia should be used as far as possible, as they have a special 

 affinity for spermatic cells. For mounting aqueous preparations, solution 

 of Ripart and Petit, or some such mercurial fluid as those of Pacini, are in- 

 dicated. 



As to the Nebenkern, which is here so important an element, see ante, 607. 



Besides the papers quoted for cytological methods, see the following : 



DOWDESWELL (Quart. Journ. Mic. Sci., 1883, p. 336). Stain in magenta, 

 one part ; glycerin, 200 ; alcohol, 150 ; water, 150. 



CABNOY (La Cellule, i, 1885, p. 209, Arthropoda). 



GILSON (ibid., i, 1885, pp. 40, 56, 58, 87, 121, 141, and ii, 1886). Here is 

 a useful fixing medium for fresh teased preparations iodised osmic acid, 

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

 postaasium 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, Salamandra, 

 Bos. 



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

 wiss. Mik., v, 2, 1888, p. 236, and Journ. Roy. Mic. 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) ). 



RENSON (Arch, de Biol, iii, 1882, p. 302). 



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

 lication of Weigert's haematoxylin stain, see below. 



JEN SON (Arch, de Biol., iv, 1883, p. 11, et passim (Selacians and Inverte- 

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



BALBIANI (Lee. sur la Gcner. des Vertebrcs, 1879, p. 244). Double-stain 

 sections with picrocarmine 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. 



RYDEB, in WHITMAN'S Meth. of 'Research, -p. 52. Sections of hermaphrodite 

 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 eight volumes of water, washed out for five to ten minutes in alcohol 



19 



