RESEARCHES ON KARYOKINESIS AND CELL DIVISION. 85 



Review of Recent Researches ow Karyokinesis ^ and 

 Cell Division. By J. T. Cunningham, B.A., Scholar 

 of Baliol College, Oxford. (With Plate VI.) 



The following is a short account of the latest investiga- 

 tions into the metamorphosis which nuclei undergo in the 

 process of indirect division, and of the present state of 

 knowledge and speculation concerning the structure of the 

 cell and the phenomena of its life." 



Methods of Examination.' — The structure of the nucleus 

 and cell, and the forms which the elements of the nucleus 

 assume during division, can only be made out clearly in 

 preparations from tissues which have been fixed and stained. 

 The reagents which have been found most valuable for otiier 

 histological researches are not always to be relied on for the 

 demonstration of karyokinetic figures. Strasburger fixed 

 his vegetable tissues by placing them, when quite fresh, in 

 absolute alcohol. Others have used the salts of chromic 

 acid, which are so useful for the isolation and definition of 

 cells. Klein^ states that he has found chromate of ammonia 

 especially successful. Flemming, on the other hand, believes 

 that all fixing reagents are more or less untrustworthy, 

 except chromic acid, 1 per cent, solution, or saturated solu- 

 tion of picric acid. Alcohol and acetic acid usually produce 

 alterations, but the latter is useful in observations on fresh 

 tissues ; and Peremeschko and Flemming have obtained good 

 results by treating fresh objects with acetic acid and Bismarck 

 brown. For staining permanent preparations various dyes 

 may be employed ; heematoxylin is one of the most certain, 

 but Hermann's aniline fluid, methyl-green, saiFranin, and 

 various carmine dyes, such as alum-carmine, borax-carmine, 

 are valuable in many cases. In the study of the ova of 

 Echinoderms Fol and Flemming obtained good preparations 

 with osmic acid and carmine, but most of FlemmingV new 



' This term was first used by Schleicher (' Die Kuorpel-zelltheiluug, Arc. 

 mik. Anat.,' Bd. 16) to deuoLe the stages iu the process of division which 

 precede the formation of the equatorial plate; but it is now agreed that it 

 shall include the whole metamorphosis from the resting state of the mother- 

 cell to the retui-n lo that state in the daughter-cells {Kcipvov, nucleus ; and 

 Kivi)(TtQ, movement). 



- See Mr. Priestley's resume in this Journal, April, 1870. 



3 This Journal, April, 1879. 



■• " Beitrage zur Kentniss der Zelle," &c., iii Theil. ' Archiv Mik. 

 Anat./ Bd. xx, 1881. 



