218 CHARLES L. PARMENTER 



exactly homologous to the components of 'Ci' and 'C2.' The 

 smaller member resembles those of ' C2' and may be homologous 

 with them. It is important to note that the three last-mentioned 

 authors find that each particular condition is constant for the 

 individual in which it is found. 



Although tetrads with unequal homologues among the longer 

 chromosomes have not been observed in the Orthoptera, they 

 might possibly exist in other animals. The above observations, 

 especially those of Wenrich, offer a possible explanation for the 

 inequalities between homologues observed in Ambystoma as well 

 as in Salamandra maculosa. Furthermore, the condition found 

 in tetrad ' C2' may offer a parallel explanation for the different 

 relative lengths shown in some cases between corresponding 

 pairs in complexes of different individuals (e.g., pr. 4 and pr. 

 9). Of course much further data from both the somatic and 

 germinal chromosomes is necessary before the above can amount 

 to anything more than a suggestion. 



2. Certain inequalities might be explained as due to the 

 presence of a multiple chromosome similar to that which has 

 been described by McClung ('05, '17), in Orthoptera, by Boveri 

 ('09), Edwards ('10, '11), and Frolowa ('12), for Ascaris megalo- 

 cephala, Boveri ('11) and Edwards ('11) for Ascaris felis, Stevens 

 ('11) in Anopheles, and by King ('12) for Necturus. In these cases 

 the sex chromosome has been interpreted as being attached to one 

 of the euchromosomes, and thus there is present in the male an 

 unequal pair of chromosomes which may parallel the condition 

 in pair 9 of figure 33 and pair 12 of figure 37. In certain Or- 

 thoptera McClung ('17) finds that the accessory may be attached 

 to different chromosomes in different individuals, which lends 

 support to the possibility that this is the condition in Ambystoma. 

 The presence of an X and a Y chromosome would also produce 

 unequal homologues. 



If either of these explanations be valid, such an unequal pair 

 should appear in all the diploid complexes of approximately 

 one-half of a somewhat large number of individuals, and similar 

 conditions should be found in the maturation period. Unfor- 

 tunately, the difficulty of obtaining a sufficient number of suitable 



