StP 12 ii»u6 



ARTICLE III. 



CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA HETEROPTERA.* 



By Thos. H. Montgomery, Jr. 



The present paper treats of the behavior of the chi'omosonies in forty species of 

 the Heniiptera, wliereby especial attention is given to their number and form in the 

 maturation mitoses, and to the changes of the modified chromosomes. Then there are 

 treated from broader points of view, the modified chromosomes, chromosome difference, 

 and the facts of the number of chromosomes. This is an amplification and correction 

 of earlier researches of mine (1898, 1901 «, 19016, 1904a) upon the same species; and 

 the preparations studied were the same. as those previously used. 



Certain phenomena treated in those earlier papers are not discussed in the present 

 one, such as the conditions of the plasmosomes (nucleoli), and tlie relations of the 

 modified chromosomes in the rest stage of the spermatogonium. 



I have felt it necessary to introduce a new nomenclature, indicated in a preliminary 

 note (1906), for the different kinds of chromosolnes. Since the discovery of peculiarl}' 

 modified chromosomes in certain of tlie insects a great variety of names has been pro- 

 posed for them, and most of these sufter from a quite unnecessary length. My own 

 earlier terms " heterochromosome " and "chromatin nucleolus" were cumbersome, 

 and "accessory chromosome" and " heterotropic chromosome" sin equally in this 

 regard, while "special chromosome" and "idiochromosome " are no way self-explana- 

 tory. Therefore for the sake of uniformity but more especially sinjplicity in wi'iting 

 I here employ tlie following nomenclature : 



Chromosome, the original term of Waldeyer (1888), to l)e retained as a convenient 

 collective word for each separate mass of chromatin and liniii. When there are no 

 marked differences in the behavior of the several chromosomes of a cell, all may be 

 given this name. But when chromosomes of diffei'ent behavior occur, they are dis- 

 tinguished as follows : 



(1) Autosome {autosomu),-ihe non-aberrant chromosomes that I have previously 

 called ordinary chromosomes. 



(2) Allosome {allosoma), any chromosome that behaves difierently from the auto- 

 somes, and is a modification of the latter. This term is much more concise than ni}' 



* CoDtribntioDS from the Zoological Laboratory of the University of Texa.s, no. 72. 

 A. P. S.— XXI. J. 21, 7, '06. 



