540 CLARENCE E. McCLUNG 



(11) the behavior of the chromosome in maturation and fertili- 

 zation is strictly in accord with the necessary mechanism for 

 alternative inheritance; (12) the inner constitution of the 

 chromosome is such as to afford an explanation for the linear 

 arrangement of factors and for their variations; (13) in the in- 

 stance of the most thorough analysis of characters in any one 

 animal, Drosophila, the groups of linked characters and their 

 ma,gnitudes correspond to the number and size of the chromo- 

 some; (14) experimental disturbance of chromosome conditions is 

 followed by the expected modifications of characters during de- 

 velopment; (15) from the known conditions of nuclear organiza- 

 tion in relation to character development predictions with re- 

 gard to new characters and combinations of characters may be 

 made. 



As has been stated before, the number of diploid chromosomes 

 in the various species of Acrididae is usually twenty-thi-ee in the 

 male. Exceptions to this have been announced by Granata ('10) 

 for Pamphagus and by various authors for Chorthippus, and by 

 myself for Hesperotettix and Mermiria. IVlontgomery gave the 

 number twenty for Syrbula acuticornis, but this is unques- 

 tionably an error, as Robertson has shown. In no case has a 

 variation been reported for cells of the individual. The gametic 

 complex therefore maintains itself, according to the reports of 

 all investigators. Similar constancy prevails in the species, in 

 almost all instances, except for the wide variation of eighteen to 

 twenty-three here reported for Hesperotettix viridis. In the 

 face of the admitted validity of numerical constancy as one test 

 of the theory of chromosome individuahty, how can it be upheld 

 when actual variations of this magnitude exist? This would 

 seem to be as severe a strain as it could be subjected to, and if it 

 can be shown that the conditions in H. viridis are capable of 

 explanation without invaUdating the hypothesis, then other 

 cases of apparent exceptions would be less weighty as evidence 

 until their full character became knowTi beyond question. 



On first thought the conditions in this group would seem to 

 be a particularly strong argmnent against the theory. Here is a 

 species, beyond question intimately related to many others of a 



