ill llic Ani'iiml KiiKjduin. 373 



follows: — " 'J'lie whole intcnwil epithelial lube, as well as a 

 iinniher ot' stn;ili»'r cells which I am inclined to rej^ard 

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

 iinmber of ei)ithelial islets remain behind, nestlint^ closely 

 against the at pres(>nt undissolved Inrval muscular layer." 



According to Carnoy {Joe. 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-develo))ed muscle-fibres of all Arthropods 

 he invariably observed direct nuclear division only^; from 

 this we can raise no objection against the views repi'esented 

 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 wdiether the amitotic 

 division occurs in the nuclei of spermatogonia or in those of 

 the snj)|)orting- (com))anion- or fluid- furnishing [Begleit- oder 

 Saft-]) cells which have a secretory function. In the latter 

 amitotic division may be expected ; but certain statements 

 exist, according to wliich it occurs in spermatogonia ; these 

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

 Eath is at present working at this question in the Zoological 

 Institute here, I will not further discuss it t- 



AA'e shall not be surjirised to find that amitotic nuclear 

 division occurs in the cells of the fat-bodj 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 

 {luc. cit.) describes the amitotic division of the nuclei of cells 

 of the fat- body, an-i mentions that, in consequence of the 

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



Miisca votnitoria," Zool, Jahrbiicher, Abt. fiir Anat, u. Outog., iii. Bd., 

 1889. 



* "With reference to tliedh-ect nuclear division observed in tbe muscle- 

 cells of Vertebrates, Flemuiing- declares (/oo. cit. p. 290) that it plays no 

 part in the physiological growth of the muscles, and that the amitotic 

 multiplication of nuclei occurring in the pathological regeneration of 

 musc'le-hbrt s has the value of a phenomenon of degeneration. As supple- 

 rac-nting this I may further refer to Robert's paper, '• Versuche iiber die 

 Wiederbilduug queigestreifter Muskeli'asern ' (Ziegler's Beitriige zur 

 pathol. Anatumie uud allgem. Pathologie, x. Bd., 1891, p. 109), according 

 to which, in the multiplicatii. n of ceils which give rise to the young 

 muscle-fibres, mitotic division exclusiAely occurs. 



t 1 refer tlie reader to the communication from O. vom Ratli, which is 

 ai.out to appenr in the * Zool. Auzeiger,' on "The Iuip..rt of Amitotic 

 Nuclear Division iu tlse Testis'' ("Die Bed iilung dcr amitoii.-cheu 

 Keruteilung im Hoden"). 



