in the Animal Kingdom. 365 



According to the present stage of our investigations we 

 may assert that the amitotic division of the nucleus always 

 indicates the end of the series of divisions. Where this mode 

 of division appears, only a limited number of divisions, or only 

 very few, or none at all take place, while the nuclei which 

 divide by mitosis possess an unlimited capacity for multipli- 

 cation for the whole duration of the life of the individual. It 

 is even a priori hardly probable that nuclei which have arisen 

 by amitotic division will ever divide again by mitosis; for in 

 amitotic nuclear division the distribution of the chromatin 

 takes place in a rough and usually very irregular fasliion ; in 

 consequence of this, mitosis, which effects a methodical and 

 altogether equable division of the chromatin, would subse- 

 quently have no importance at all and no further value, or it 

 would at least remain quite unintelligible. 



Flemming shows {loc. cit.) that, in the amitotic division of 

 the nuclei of leucocytes, in connexion with the constriction of 

 the nucleus a division of the attraction-sphere and of its central 

 body does not take place *. Into connexion with the absence 

 of this division it is perhaps possible to bring the fact that 

 division of the cell does not usually follow amitotic nuclear 

 division. As Flemming remarks, further investigations will 

 have to decide whether, in those cases in which amitotic 



* This observation gives an important support to the view that the 

 processes of amitotic nuclear division and of branching of the nuclei are 

 connected with and merge into one another ; the unusual size also is a 

 feature common both to the nuclei which are branched and to those 

 which divide without mitosis. Korschelt (" Beitrage zur Morphologie 

 und Physiclogie des Zellkerns," Zool. Jahrbiicher, Abteilung fiir Anat. 

 und Ontogenie, Bd. iv., 1889) has shown in comprehensive fashion that 

 branched nuclei frequently occur in cells such as those in which an intense 

 secretion takes place. The branching of the nuclei points to the fact that 

 they have adapted themselves to a large extent to the specialized physio- 

 logical function, and this far-reaching adaptation involves the destruction 

 of the nuclei after a longer or shorter interval. That there is a physio- 

 logical and morphologiciil connexion between the amitotic division and 

 the branching of the nuclei is also to be deduced from the fact that they fre- 

 quently occur side by side ; for instance, in some preparations of the whole 

 of the alimentary canal of Porcellioscaber (which l)r. vom Rath most kindly 

 allowed me to examine) I observed that the nuclei of the epithelium of 

 the posterior half of the mid-gut exhibited manifold ramitications and 

 here and there the figures of direct division. 1 would remark in passing 

 that forms of nuclei such as we meet with in this instance have been 

 described and figured by van Bambeke (" Des deformations artificielles 

 du Noyau," Archives de Biologie, t. vii., 1887), but that I am unable to 

 discuss his paper further, because I am not perfectly clear as to what van 

 Bambeke wishes to convey by the expression " Deformation artiticielle." 

 It will perhaps be advisable to make a subdivision for those cases of 

 amitotic nuclear division which occur in conjunction with branching of 

 the nuclei. 



