m the A/iiinal Kingdom. 373 



follows : — " The whole internal epithelial tube, as well as a 

 number of smaller cells which I am inclined to regard 

 as connective tissue, is cast otf into the lumen. Only a 

 number of epithelial islets remain behind, nestling closely 

 against the at present undissolved larval muscular layer." 



According to Carnoy (loc. cit.) amitotic nuclear division in 

 the Arthropods is also met with in the nuclei of the muscle- 

 fibres and in the nuclei of the testicular tubes. Carnoy main- 

 tains that in fully-developed muscle-fibres of all Arthropods 

 he invariably observed direct nuclear division only^; from 

 this we can raise no objection against the views represented 

 above, since it is easily conceivable that the nuclei of mature 

 muscle-fibres adapt themselves to their special physiological 

 functions. As regards the nuclei of the testicular tubes, we 

 must naturally strictly distinguish whether the amitotic 

 division occurs in the nuclei of spermatogonia or in those of 

 the supporting- (companion- or fluid- furnishing [Begleit- oder 

 Haft-]) cells w'hich have a secretory function, in the latter 

 amitotic division may be expected ; but certain statements 

 exist, according to which it occurs in spermatogonia ; these 

 cases must be submitted to fresh investigation. As Dr. vom 

 Rath is at present working at this question in the Zoological 

 Institute here, I will not further discuss it !• 



We shall not be surprised to find that amitotic nuclear 

 division occurs in the cells of the fat-body of Arthropods ; 

 for these cells, in their physiological function, are adapted to 

 the storing-up of nutritive material, and disintegrate if the 

 nutritive material is used to build up other tissues. Carnoy 

 [loc. cit.) describes the amitotic division of the nuclei of cells 

 of the fat-body, and mentions that, in consequence of the 

 absence of cell-division, cells with several nuclei (from two to 



Musca votnitoria" Zool. Jahrbiicher, Abt. fiir Anat. u. Ontog., iii. Bd., 

 1889. 



* With reference to the direct nuclear division observed in the muscle- 

 cells of Vertebrates, Flemniing- declares {loc. cit. p. 290) that it plays no 

 part in the physiolooical growth of ihe muscles, and that the amitotic 

 multiplication of nuclei occurring in the pathological regeneration of 

 muscle-tibrt s has the value of a phenomenon of degeneration. As supple- 

 menting this 1 may further refer to Hubert's paper, '• Versuche iiber die 

 Wiederbildung c[uerget.treifter Muskeifasern ' (Ziegler's Beitrage zur 

 pathol. Anatomie und allgem. Pathologie, x. Bd., 1891, p. 169), according 

 to which, in the multiijlication of cells which give rise to the young 

 musele-tibres, mitotic division exclusively occurs. 



t I refer tlie reader to the communication from O. vom Rath, which is 

 about to appear in the 'Zool. Anzeiger,' on "The Import of Amitotic 

 Nuclear Division in the Testis" ("Die Bediitung der auiitoliclieu 

 Kernteilung im Hoden"). 



