80 



Journal of Applied Microscopy. 



The Demonstration of Karyokine- 

 sis. 



By B. F. Kingsbury. 



Recent inquiries, one of them from an 

 American medical college, seeking infor- 

 mation as to methods of demonstrating 

 the indirect division of cells, or k'aryo- 

 kinesis, suggest that there may be others 

 to whom as teachers or private workers 

 a few hints as to material and methods 

 will be helpful. Indeed, the writer's per- 

 sonal experience permits him to appre- 

 ciate the help that may be afforded by 

 such suggestions as are here intended. 

 There certainly appears to be a lack of 

 any specific suggestions or directions, 

 those being most satisfactory that are 

 contained in Whitman's* Methods of 

 Microscopical Anatomy and Von Kahl- 

 den'st Pathological Histology, in neitlher 

 of which is there suitable information 

 as 'to material. 



Nothing original is offered save per- 

 haps a few observations on favorable 

 forms for American workers, the inten- 

 tion being simply to present clearly a 

 few standard methods in use here and 

 elsewhere by means of which prepara- 

 tions may be obtained that will fulfill 

 most of the desiderata in the demon- 

 stration of karyokinesis, i. e., the oc- 

 currence of all the stages in the same 

 preparation, showing well the chromatic 

 and achromatic figures in cells of a size 

 well suited for class demonstration. 



Since Schneider, in 1873, first estab- 

 lished the occurrence in cell division of 

 the intricate phenomena constituting 

 what Is variously termed karyokinesis, 

 mitosis, or indirect cell (nuclear) division, 

 we have had demonstration of it in all 

 groups of animals, from the protcfzoa to 

 man, and in plants from the algae to the 

 higher phanerogams, and the earlier con- 

 ceived direct division of cells has been 

 found to be of rarer occurrence. For 

 demonstration, however, attention was 

 soon confined to narrower limits and a 

 choice is given of Amphibia and the eggs 

 of Ascaris megalocephala, the parasitic 

 round worm of the horse, and of the 

 Echinodermata (sea-urchins, etc.) Among 

 plants, the young embryo-sack of Fritil- 

 laria and the developing pollen cells of 

 the miembers of the Liiliaceae appear to 

 have been favorite objects for demon- 

 stration. It is interesting to observe how 

 closely anatomies published after 1885 

 confine themselves to these three groups 

 for illustration of cell-division, with othei 

 forms, of course, occasionally supple- 

 menting or supplanting. 



The Amphibia are by far the favorites,^ 

 both because of the large size of the* 

 cells, their availability, and the pioneer 

 work done upon them by Flemming t and 

 Rabl,[| whose figures are often copied. 

 Both the larval and adult animals may 

 be used. Karyokinesis, however, is best 

 shown in special localities; in the adult 

 the testis, corneal epithelium, and epi- 

 thelium of the tongue; in the larva the 

 epidermis, oral and branchial epithelium. 

 The epithelium of the lung and peri- 

 toneal cavity have also been employed. 

 It is to be noted that the forms on w'hich 

 work has been done, and to which ref- 

 erences in the literature apply, are 

 almost exclusively European, Salaman- 

 dra and Triton, and some may not real- 

 ize the availability in America of forms 

 fully as serviceable as either of these. 



Of the organs above mentioned, the 

 testis seems on some accounts most to 

 be preferred, the only objection being 

 that the results are dependent on the 

 breeding habits of the animal and there- 

 fore on the time of year. Salaman- 

 dra, the European form so much worked 

 on, mates early in the spring, and, as 

 Flemming** first made known, spermato- 

 genesis occurs as a yearly cycle begin- 

 ning with the breeding season. After the 

 deposition of the spermatozoa, there is a 

 general increase in the size of the testis 

 during the spring months, caused by a 

 multiplication of the residual cells (sper- 

 matogonia). This is most vigorous dur- 

 ing the late spring and early summer. 

 May to July. In July and the first part 

 of August the final divisions take place 

 and the maturation of the zoosperms 

 begins, extending well into the fall. The 

 winter is spent with the testis in a rest- 

 ing state, charged with ripe spermatozoa. 

 Thus, in order to obtain karyokinesis, it 

 is necessary to use animals taken during 

 the late spring or early summer. 



In America, we are favored with a 

 larger number of forms with a greater 

 range of habits, allowing us to be some- 

 w^hat more independent of the time of 

 year. Diemyctylus (viridescens, repre- 

 sented on the Pacific slope by torosus), 

 the vermillion-spotted newt, in its range 

 and the ease with w'hich it may be 

 obtained from ponds and ditches in 

 the eastern United States, is perhaps 

 most available of our forms; it is, how- 

 ever, quite nearly related to the Euro- 

 pean salamanders and resembles them 

 closely in its mating habits and sperma- 

 togenesis, making it available for the 

 demonstration of cell-division only dur- 



*Whltman, C. O. Methods of Research 

 in Microscopical Anatomy and Embryology. 

 Boston, 1885. 



tKahlden, C.von. Methods of Pathological 

 Histology. Translated by H. M. Fletcher. 

 London, 1894. 



JFlemming, W. ; Zellsubstanz, Kern und 

 Zelltheilung. Leipzig, 1882. 



MRabl, C; Ueber Zelltheilung. Morph. 

 Jahi'buch, Vol. X, 1884-85.; pp. 214-330. 



**Flemming, W. ; Neue Beitraege zur 

 Kenntniss der Zelle. Arch. f. mikr. Anat., 

 Vol. XXXIX, 1887, p. 389. 



