274 CHROMATIN, ANIMAL CHROMOSOMES, NUCLEOLI 



sufficient, though a longer time works well. Next the slides are 

 placed in a jar of 95 per cent, alcohol where they may be left over- 

 night or longer. Here a few of the coverslips will loosen and may 

 even come off. If they do not, they are pried off with a needle 

 ground to a spade-like edge and mounted directly in euparal, 

 further dehydration being unnecessary. With a little care the 

 coverslip may be put back into the same position it had wheji it 

 was pried off. 



When the coverslip is pried off, as described above, some of 

 the tissue will stick to the slide, some to the cover and some will 

 come loose and be lost in the mounting process. Bauer (com- 

 municated by letter) has found that the following treatment of 

 the slides and coverslips will remedy this trouble : Before use, 

 the slides are given a thin coating of egg albumin, which is allowed 

 to dry. The under side of the coverslip is coated with a thin 

 layer of oil (run your finger tips through your hair and then rub 

 the underside of the cover with them). This will keep the chromo- 

 somes from sticking to the coverslip when the nuclei are crushed. 



If one wishes to employ Feulgen's stain, from the 95 per cent, 

 alcohol the slides are brought through the lower grades to water 

 and then fixed a few minutes with Bouin-AUen (presumably other 

 fixatives will do also), washed in running water, after which they 

 are treated and stained in the usual way (§ 623). 



643. Other Examples. For orthopteran chromosomes Carothers 

 {Jour. Morph., xxviii, 1916) recommends a modification of Bouin's 

 fluid (see § 115), which is currently widely used. Minouchi (Zeitschf. 

 Zellforsch.' u. mikr. Anat., xx, 1934, p. 709) finds the best fixation, 

 after the use of diluted Flemming's solution from which all acetic acid 

 is omitted. Dilute two or three times with distilled water. 



For lepidopteran chromosomes Seiler has used Carnoy's 6:3:1 

 mixture for testes and Petrunkevitch's fluid for eggs {Arch. Verer. 

 Social u. Rasshygiene, i, 1925, p. 63). Goldschmidt {Arch. f. Ent. d. 

 Org., cxxvi, 1932, p. 591) recommends the use of Bouin-Duboscq for 

 such material. 



For crustacean testes, Bouin-AUen has been used with good results. 

 More recently, Niiyama {Jour. Fac. Sci., Hokkaido Imp. Univ., iii. 

 1934, p. 4) finds that Champy's fluid diluted with an equal part of 

 water works well with a fresh-water crayfish. For the edible crab, one 

 should use sea water for dilution {ibid., iv, 1935, p. 59). 



For arachnida, Sokolow {Zeitsch. f. Zellforsch u. mikr. Anat., xxi, 

 1934, p. 42) recommends that the testes be dissected out from the liver 

 in a 0-75 per cent, solution of sodium chloride. Aceto-carmine pre- 

 parations give excellent figures, but if sections are required, such fixa- 

 tives as Flemming's, Champy's or Navaschin's work well. 



For annelid chromosomes Huth reports that for meiotic and first 

 cleavage stages in eggs, Bouin or Bouin-Allen give excellent results. 

 For earlier stages of the ovary, and for testes, Flemming's or Navaschin's 

 fluids are much better {Zeitsch. f. Zellforsch. u. mikr. Anat., xx, 1933, 

 p. 309). 



For trematode eggs, Minouchi fixes (Polystomum intergerrimum) for 

 thirty to forty minutes in Carnoy's 1:1:1 mixture and then replaces 



