374 Dr. H. E. Ziegler on Amitotic Nuclear Division 



ten) are frequently met with *. Tlie consumption of the cells 

 of the fat-body has been minutely observed by van liees {loc. 

 cit. pp. 76-83) in the pupa of Jlusca vomitoria. " It is not 

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

 as food by the leucocytes of the pupa. I have found that 

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

 and are at any rate partially destroyed 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. Most of them lay in the 

 immediate neighbourhood of the nucleus, some few in the 

 protoplasmic net of the fat-cell between the small fat-granules. 

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

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

 than a hundred leucocytes were collected round the nucleus 

 of the fat-cell ; the nucleus steadily loses stainable matter, so 

 that the idea naturally arises that the latter is dissolving and 

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

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

 cells disappears, and another portion later still. The leuco- 

 cytes now disperse through the Huid 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 find in tlie Echinorhynchi a typical 

 example of amitotic nuclear division. According to Ha- 

 mann's f careful description the nuclei 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 ents Irequently occur. JSince the limits of the cell have 

 di^a] peared there can be no question of a division of the cell 

 following on division of the nucleus. The function of the 

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

 known, the Echinorhynchi possess no alimentary canal, and 

 are nourished by osmosis through the skin ; vacuoles are 

 foimed in the dermal layer which coalesce into a lacunar 

 system ; the kuniisci, which have arisen as local thickenings 

 of the dermal layer, are traversed by large cavities, which are 



* In Vertebrates, too, we find several nuclei in the fat-cells in many 

 kinds of absorption of fat (FJemming, Archiv fiir niikrosk. Anatomie, 

 Bd. 7, 1871, pp. 71, 330, 357, note ; and Virchow's Archiv, 1872). Since 

 the observations in question date from an earlier period, in which no 

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

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



t O. Hamann, "Monooraphie der Acanthocephalen (Echinorlivnchen)," 

 Jenaische Zeitschrift, 25 Bd., 1800, pp. UO and 215. 



