374 Dr. II. E. Ziegler on Amitutic Nuclear Division 



ten) are frequently met ^vitll *. The consumption of the cells 

 of the fat-hody has been minutely observed by van Rees (/oc. 

 cit. pp. 7G-83) in the pujia of Musca vomiloria. " It is not 

 only the muscles of the larva," he writes, " which are utilized 

 as tood by the leucocytes of the pupa. 1 have found that 

 the fat-cells also are attacked by them, serve them as food, 

 and are at any rate partially destroyetl by them. On the 

 third day I was able, by examining sections, to recognize with 

 certainty the presence of a small number of blood-corpuscles 

 in the interior of these fat-cells. ]\lost of them lay in the 

 immediate neighbourhood of the nucleus, some few in the 

 proto[)lasmicnet of the fat-cell between tlie small i'at-granules. 

 In some blood- corpuscles I found frum two to three nuclei, or 

 even six or a still larger number. (Jn the sixth day more 

 than a hundred leucocytes were collected round the nucleus 

 ot the fat- cell ; the nucleus steadily loses stainal)le matter, so 

 that the idea naturally arises that the latter is dissolving and 

 is being conveyed to the blood-corpuscles by osniosis. It is 

 not until several days have elapsed that a portion of the fat- 

 cells disa])pears, and another portion later still. The leuco- 

 cytes now disperse through the lluid of the body, and we are 

 then able to distinguish, besides leucocytes with only a single 

 nucleus, others which possess several nuclei, even as many as 

 twelve." 



Among the Worms, we tind in the EchinorhyncJii a typical 

 example of amitotic nuclear division. According to Ha- 

 mann's f careful description the luiclei of the dermal layer 

 and those of the lemnisci grow to an enormous size and fre- 

 quently exhibit branched and lobate forms. Constriction 

 into two equal or unequal parts or resolution into several 

 fragn cuts Irequently occur, ISince the limits of the cell have 

 dif-a] peared there can be no question of a tlivisiou of the cell 

 following on division of the nucleus. The function of the 

 nuclei is manifestly that of assimilation ; for, as is well 

 known, the Ecliinorhynchi ])ossess no alimentary canal, and 

 are nourished by osmosis through the skin ; vacuoles are 

 ibimed in the dermal layer which coalesce into a lacunar 

 systini; the hnniisci, which have arisen as local thickenings 

 oi the dermal h'ver, are traversed by large cavities, which are 



* In Vertebrates, tuo, Ave timl .-everal iiiuloi in the fat-cells iu mariv 

 liiiidtt ol" absorytii.n of fat (Fleuiuiinir, Areliiv fiiv inikrosk. Aiiatoiuie, 

 Ed. 7, ]fS71, pp. 71, o;^0, ■M^>7, note; ami Vircbcnv's Arehiv, 187-). Since 

 tl;e observations in question date from an earlier period, iu wiiich no 

 attention was as yet paid lo the difference between mitotic and amitotic 

 division, tiie case in this respect is not yet clear. 



t (•• Unniann. "Monountphie der Acantluvophalpu ( I'lchiui rhvurhen)." 

 Jenaische /eilschrift, I'o Jld.. \>\\\ pp. 1 U> and iM-"). 



