M'CLUNG : SPERMATOCYTE DIVISIONS OF THE ACRIDID.E. 95 



some plants, and is thus long established in relations that differ from 

 the ordinary resting nucleus. Because this spireme in the spring 

 divides into half the number of segments that the spermatogonia! 

 spireme did, are we justified in assuming that each of these segments 

 represents two longitudinally arranged chromosomes of the early cell 

 generation? It would appear that, with our present knowledge of the 

 subject, we are not; and certainly it would be less prejudicial to an 

 impartial study if this fact were made clear in discussions upon the 

 question. 



Under the term "nucleolus," Henking discusses a structure which 

 appears to be identical with that which I have termed the accessory 

 chromosome. I am led to this belief by the statements he makes 

 concerning the constancy of staining power, position in the nucleus, 

 and regularity of outline. In all these features there is a striking re- 

 semblance between the elements. Regarding these points he says : 

 "Erscheint der Nucleolus der jiingsten Hodenzellen bei der genann- 

 ten Methode farblos, so nimmt er nun begierig Farbe auf, ein Ver- 

 halten, welches ganz regelmassig ist. . . . Allein der Nucleolus 

 hat bei den Veranderungen von Kern und Zelle sein Aussehen nicht 

 gewechselt. , . . Der Nucleolus behalt seine Kugelgestalt un- 

 verandert bei, wahrend die Chromosomen gewissermassen Pseudo- 

 podien aussenden und sich so zu einem Netz vereinigen. Der 

 Nucleolus bietet seinerseits den Pseudopodien keine Ansatzflachen 

 und bleibt daher isoliert." 



Later, in discussing the chromosomes, he mentions peculiarities, 

 one of which puts it in agreement with the later changes undergone 

 by the accessory chromosome in Orthopteran cells. These points are, 

 again, the size, staining intensity, and smooth contour. It is asserted 

 with great positiveness that, in the last division of the spermatocytes, 

 this element goes over undivided into one of the daughter cells. 

 Certain appearances in the testicular cells of Xiphidiuin at one time 

 led me to believe that the accessory chromosome was thus apportioned 

 by the last spermatocyte division. I am not now prepared to make a 

 positive assertion upon this iDoint, but I hope by the aid of more 

 favorable material to reach a conclusion concerning the matter. Be 

 this as it may, there is an evident resemblance between Henking's 

 undivided chromosome in Pyrrhocoris and the accessory chromosome 

 of Xiphidum. In view of all these resemblances, I do not doubt that 

 the accessory chromosome has been observed by Henking. 



The observations of vora Rath (14) upon the spermatocyte divisions 

 of Gryllotalpa vulgaris give us an excellent idea of the actual division 

 of the chromosomes. The exact origin of these tetrad elements, how- 

 ever, is not clearly demonstrated. As a result of this, each of the 



