Nachdruck verboten. 



U eher setzungsrecht vorbehalten . 



Contributions to a knowledge of the Nebenkern in the 

 Spermatogenesis of Pulmonata — Helix and Arion. 



By 

 J. A. Murray, B. Sc, Edinburgh. 



(From the Zoological Institute of the University of Würzburg.) 



With Plate 32 and 33. 



The investigation detailed in the following pages was commenced 

 at the suggestion of Prof. Boveri and carried out in his laboratory 

 during the summer sessions 1895, 1896, 1897. 



It is a pleasant duty to acknowledge the liberality with which 

 Prof. Boveri has always put the resources of his well-appointed In- 

 stitute at my disposal and his valuable advice and criticism. 



My thanks are also due to Prof. Balfour of Edinburgh for the 

 use of his laboratory during the autumn of 1895 and 1896; and to 

 Prof. Hermann of Erlangen for the use of several extremely beauti- 

 ful and instructive preparations. 



I. Historical. 



This work was instituted as a control to the observations of 

 Platner, whose views, in spite of several attacks from various sides, 

 are still generally accepted by cytologists. 



The latest and most complete exposition of the behaviour of the 

 Nebenkern in mitosis, given by Platner, is contained in the com- 

 munication titled : Beiträge zur Kenntniss der Zelle und ihrer Theilungs- 

 erscheiuungen. I. Zelltheilung und Samenbilduug in der Zwitterdrüse 

 von Limax agrestis, in: Arch. mikr. Anat., V. 33, p. 125. Briefly 

 this is as follows: The Nebenkern never disappears entirely but only 

 undergoes peculiar changes in form. The number of "rods" making 



Zool, Jahrb. XI. Abth, t. Morph. 28 



