i^46 Miscellaneous. 



muscle-fibres and generally several blood-spaces. Although I have 

 been unable to trace branches of the pallial nerves into these 

 tentacles, I have traced them to their bases, and there can be little 

 doubt that they are supplied by fibres from these nerves. 



If, then, we consider the following points — -Ist, the specialized 

 tentacle is marginal in formation, and is carried back with the 

 siphons during their development, and more especially by their 

 retraction ; 2nd, it is placed sometimes on the right and sometimes 

 on the left side, -sNhich may indicate that it is an organ of late 

 specialization, not thoroughly settled in position ; and 3rd, it re- 

 ceives its nervous supply as a branch of the same nerve which 

 supplies the marginal tentacles — it may be justifiable to call atten- 

 tion to a possible homology between the specialized tentacle and a 

 marginal tentacle which has become slightly modified in structure 

 and very much enlarged and specialized. — Johns HopTcins University 

 Circulars, June 1896, pp. 85, 86. 



Some Ohservations on S^yermatogenesis in Spiders. 

 By Julius Wagner, of St. Petersburg. 



My investigations in the course of last year have yielded results 

 which diiTer so greatly from the observations of Gilson (' La 

 Cellule,' t. i.) that I do not consider it superfluous to communicate 

 them, although my studies are not yet completed. The main part 

 of the work was carried out in the Zoological Institute at Heidel- 

 berg, and I feel impelled to avail myself of this opportunity of 

 expressing to Hofrath Prof. Biitschli my best thanks for his constant 

 attention and never-failing guidance. 



(1) Cell-boundaries between the spermatogones do not exist 

 during the earlier stages. The delimitation of the bodies of the 

 cells takes place at different times according to the species, and in 

 consequence of this the spermatogones of the last generation may 

 be both uni- and multinucleate. 



(2) The division of the nuclei of the spermatogones, while not 

 following the ordinary plan of karyokinesis, is nevertheless not 

 amitotic. 



(3) In the transformation of the nucleus of the spermatogone 

 into that of the spermatocyte the former network of linin gives rise 

 to a linin-thread or to a few such threads. The nuclei come to 

 assume an excentrie position ; the whole of the linin passes over 

 with the chromatin granules into one half of the nucleus, namely 

 into that which is adjacent to the periphery of the cell. The linin- 

 thread (or the rows of the chromatin granules) forms loops, all of 

 which are of the same length and have the same direction ; in this 

 way the linin-thread divides into portions of equal length. Simul- 

 taneously the formation of the nucleolus takes place. 



(4) The granules of archoplasm collect in the narrow space which 

 remains between the chromatin half of the nucleus and the surface 

 of the cell. In the interior of the collection of archoplasm thus 



