MULTIPLE CHROMOSOMES 523 



twenty-one ordinary rods. That there is here a true preserva- 

 tion of the physical identity of each member of the complex is 

 evident from the continued characteristic behavior of the mem- 

 bers which are apparently fused together. The conception of 

 genetic continuity is therefore not merely formal, but expresses 

 the actual morphological conditions of the species. Aside from 

 the presence of the multiple chromosome the germ cells show no 

 marked difference from moBt other Acrididae. 



To complete my former account of the chromosomal charac- 

 ters of this species the following facts may be given : In the sper- 

 matogonium appear twenty-one rod-shaped chromosomes which 

 are generally characteristic of the Acrididae. Besides these 

 there is a V-shaped element with arms of unequal length (fig. 

 9, pi. 3). That this is not a simple euchromosome is indicated 

 by the observation that one member becomes highly vesicular 

 during the prophases. Such a condition is uniformly charac- 

 teristic of the accessory chromosome under these circumstances 

 and is sufficient to identify this arm of the V as the accessory 

 chromosome. During the synapsis stage there is joined to this 

 heterogeneous pair a third member, the homologue of the euchro- 

 mosome portion. In the late prophase the accessory chromo- 

 some is precocious in condensation and appears as a dense, 

 homogeneous rod, more or less bent, joined to a granular tetrad 

 by endwise union. The contrast is most evident in preparations 

 by the tri-color stain. In the first spermatocyte metaphase this 

 hexad element goes on the spindle ^\ith its long axis parallel 

 to that of the spindle and having fibers attached at the ends of 

 the tetrad. This brings one fiber to the point of union between 

 the accessory chromosome and the tetrad. There are visible, 

 at this time, eleven separate chromosomes, of which ten are 

 quite like the ordinary Acrididaean type while the eleventh is the 

 cane-shaped multiple (complex 6, pi. 1). 



The anaphase groups resulting from this division each show 

 eleven chromosomes, but in one there is a V which has no like 

 mate in the sister group. This is constituted of the accessory 

 chromosome and one half of the tetrad. In the second sper- 

 matocyte into which the V goes, the nature of this is again Hke that 



