m'clung: spermatocyte divisions of THE LOCUST1D.K. 223 



allonge's, ijue Ton reconnait dans les nuck'oles, ^galement volumineux et al- 

 longes, des spermatocytes de premier ordre en prophase. A la m^ta phase de la 

 premiere cinese, on le trouve situ(; excentriquement et plus presde l'undes poles; 

 il va tout (utter a Vune d> .s cdlaU s-fi/lcs. Dans celle-ci, il ee divise comme 

 un chromosome ordinaire, d'ou il suit que sur quatre spermatides furmont la 

 descendance d'un spermatocyte, dtux se trouvenf /rri rifegiees. Par ce 

 partage int'gal, non realise dans Xiphidium fasciatum, d'apres McClung, le 

 chromosome special d'Orphania rappelle celui des h^mipleres." 



A like series of processes is recognized in the Phasmids. 



As is elsewhere explained in this paper, the occurrence of two 

 divisions of the accessory chromosome in Xiphidium, which was 

 mentioned as a possible occurrence in my preliminary paper, is 

 shown not to take place. While it is much more difficult to 

 demonstrate the undivided condition of the accessory chromo- 

 some in one of the spermatocyte mitoses of Xiphidium than it is 

 in the cells of Orchesticus, Anabrus, Scudderia, and Microcentrum, 

 I am convinced that it does not differ from the other Locustids 

 in this respect. 



We may therefore feel assured that our knowledge of the 

 morphological character of the accessory chromosome in the 

 Orthoptera is fairly well established. This gives us a good 

 base from which to conduct further comparative studies into 

 other groups, and it is to be hoped that our knowledge of this 

 element will rapidly increase. 



Unfortunately, de Sinety has chosen to add another name to 

 the already overburdened list of synonyms, and "chromosome 

 special" now takes its place in the literature of insect sperma- 

 togenesis. The reason for adding this name — 



"II reeu successivement les noms de 'accessory chromosome' (McClung), 'small 

 chromosome' (Paulmier), 'chromatin nucleolus' (?), 'chromosome .»•' (Mont- 

 gomery). Nous avons pre'fere' C-viter ces appellations, qui semblent toutes 

 supposer une signification qui n'a jamais 6t6 d^finie ou s'appuyer sur des car- 

 acteres plus ou moins secondaires, pour adopter un nom indifferent, celui de 

 'chromosome special,' nous conformant a l'id^e de Wilson, pour qui e'est un 

 'extra chromosome,' " 



would seem to be at least insufficient, since "accessory chromo- 

 some" can scarcely be regarded as implying any more primary 

 or secondary function than can "chromosome special." 



(/) Individuality of the Chromosomes. 

 In each of my preceding papers I took the opportunity to 

 point out the fact that, even were the accessory chromosome 



