DIRECT OR AMITOTIC DIVISION 83 



cells and polymorphic nuclei are thus often formed. These and 

 many similar facts led Flemming in 1891 to express the opinion that 

 so far as the higher plants and animals are concerned amitosis is "a 

 process which does not lead to a new production and multiplication 

 of cells, but wherever it occurs represents either a degeneration or an 

 aberration, or perhaps in many cases (as in the formation of multi- 

 nucleated cells by fragmentation) is tributary to metabolism through 

 the increase of nuclear surface." ^ In this direction Flemming 

 sought an explanation of the fact that leucocytes may divide either 

 mitotically or amitotically(t. Peremeschko, Lowit, Arnold, Flemming). 

 In the normal lymph-glands, where new leucocytes are continually 

 regenerated, mitosis is the prevalent mode. Elsewhere (wandering- 

 cells) both processes occur. " Like the cells of other tissues the 

 leucocytes find their normal physiological origin (Neubildung) in 

 mitosis ; only those so produced have the power to live on and repro- 

 duce their kind through the same process." ^ Those that divide ami- 

 totically are on the road to ruin. Amitosis in the higher forms is 

 thus conceived as a purely secondary process, not a survival of a 

 primitive process of direct division from the Protozoa, as Strasburger 

 (82) and Waldeyer ('88) had conceived it. 



This hypothesis has been carried still further by Ziegler and vom 

 Rath ('91). In a paper on the origin of the blood in fishes, Ziegler 

 ('87) showed that the periblast-nuclei in the eggs of fishes divide 

 amitotically, and he was thus led like Flemming to the view that 

 amitosis is connected with a high specialization of the cell and may 

 be a forerunner of degeneration. In a second paper ('91), published 

 shortly after Flemming's, he points out the fact that amitotically 

 dividing nuclei are usually of large size and that the cells are in 

 many cases distinguished by a specially intense secretory or assimi- 

 lative activity. Thus, Riige ('90) showed that the absorption of 

 degenerate eggs in the amphibia is effected by means of» leuco- 

 cytes which creep into the egg-substance. The nuclei of these 

 cells become enlarged, divide amitotically, and then frequently 

 degenerate. Other observers (Korschelt, Carnoy) have noted the 

 large size and amitotic division of the nuclei in the ovarian follicle- 

 cells and nrtritive-cells surrounding the ovum in insects and Crusta- 

 cea. Chun found in the entodermic cells of the radial canals of 

 Siphonophores huge cells filled with nests of nuclei amitotically 

 produced, and suggested ('90) that the multiplication of nuclei was 

 for the purpose of increasing the nuclear surface as an aid to 

 metabolic interchanges between nucleus and cytoplasm. Amitotic 

 division leading to the formation of multinuclear cells is especially 



1 ' 



91, 2, p. 291. 



