584 CLARENCE E. McCLUNG 



We confront two alternative explanations for this re-integration 

 of the chromosomes; either they actually persist as discrete 

 units of extremely variable form, or they are entirely lost as 

 indi\ddual entities and are reconstituted by some extrinsic 

 agency. There is no other possible explanation and we must 

 weigh the evidence for one or the other of the alternatives. 



All facts which indicate order and system, in chromosome 

 features speak for the former, those which demonstrate varia- 

 bility and indefiniteness, for the latter. The case for discontin- 

 uity is strongest in the absence of any chromosome order, and 

 becomes progressively weaker wdth the establishment of definite- 

 ness and precision in form and behavior. Evidence has already 

 been given in other papers on the Orthoptera to show the exact- 

 ness in organization of chromosomes, their persistent continuity 

 between mitoses in certain cases, the uniformity in number and 

 behavior through large groups, and the parallel behavior of 

 chromosomes on one hand, and of somatic characters on the 

 other. In this paper are discussed what appear to be the 

 widest departures from normal conditions so far found in the 

 group. Accepting as most important, next to actual observed 

 continuity, the evidence afforded by constancy in number, size, 

 form and behavior of the chromosome, I have been able to show 

 that these criteria are here applicable and that variation is only 

 apparent and not real. It seems to me that the facts disclosed 

 in Hesperotettix and Mermiria not only fail to weaken the case 

 against individuality, as tested by constancy in number, size, 

 etc., of the chromosomes, but, on the contrary, greatly strengthen 

 it, for the reason that all of the distinguishing features of the 

 individual chromosomes are maintained, even in the presence of 

 unions into multiples of higher order. The fact that, although 

 the number of independent units is reduced, nothing is lost from 

 the complex, is most important and significant. 



Finally, the main feature of chromosome individuality must 

 not be lost in a discussion of whether it is the chromatin or the 

 linin that persists with less change. However great in impor- 

 tance this distinction may be, it does not alter the aspect of the 

 problem of individuality in its present phase. One or both of 



