MULTIPLE CHROMOSOMES 543 



much interest to find that in Hesperotettix this portion is rela- 

 tively stable while the larger elements may be variously combined 

 together. But however much difference there may be in num- 

 bers there is apparent no loss of any morphological structures in 

 any of the classes. A comparison of homologous series of 

 chromosomes, based on size, may be made on inspection of plate 

 2 where I have attempted to arrange the chromosomes of dif- 

 ferent classes in order so that homologous chromosomes are in 

 vertical rows. In the case of multiple euchromosomes they are 

 placed in an intermediate position between the columns where 

 their members would properly come. The accessory chromo- 

 some, when in a multiple, is dra^\^l as it is attached to its tetrad. 



Even a casual inspection of this plate will show that, aside 

 from the accessory chromosome, the seven smaller chromosomes, 

 (nos. 1 to 8) constitute a graded series in which variation is not 

 great. The eighth chromosome, however, may or may not 

 have the accessory chromosome attached to form a multiple. 

 In classes 4 and 5 there are above this chromosome only two 

 other separate ones, but these are of a character to attract atten- 

 tion at once. Unlike most of the remaining elements of the 

 complex, they he extended, parallel with the spindle axis and are 

 in the form of open rings, each half of which is greater than the 

 whole of chromosome eight. There are a number of considera- 

 tions which make it practically certam that these are multiples 

 composed respectively of chromosomes 9 and 10, 11 and 12. 



First, it is to be noted that if these are counted as octad 

 multiples, the number of chromosomes becomes exactly twelve. 

 In weighing the value of this piece of e\ddence it must be re- 

 membered that this number is characteristic of ahnost the en- 

 tire family to which Hesperotettix belongs. This fact makes it 

 certain that in this respect we deal mth such a fundamental 

 feature of organization as to require us to consider any varia- 

 tion, not as prima facie evidence of a lack of precision in organi- 

 zation, but rather as a modification of the form of it.^ In the 



2 One of the most unjustifiable and unscientific attitudes imaginal)le is that 

 which would regard the effort to interpret the form of organization in its vari- 

 ous aspects only as an attempt to force a real divergence into a seeming agreement. 

 Such a style of argument has been resorted to by a number of those whose belief 



