NEW TYPES OF CHROMOSOME DISTRIBUTION. 147 



justify me in saying that the above statements are absolutely true, 

 but all the data point in that direction. I hope to reexamine the 

 form as soon as material can be procured. If, then, these 

 inferences prove true, Acholla multispinosa gives another new 

 type of chromosome distribution in which the female has four 

 more chromosomes than the male. For lack of material, I have 

 not attempted to follow the differential chromosomes through the 

 growth period. 



It was noticed in the prophase and metaphase of the first 

 division that three chromosomes (the large one and two others) 

 were joined together end to end. Montgomery described such 

 a complex in his account of the chromosomes in a species which 

 he called " Sinea diadenia." In his first paper ('01) he con- 

 sidered the large chromosome representing two bivalents, but 

 later ('06) described it as one large bivalent. All three members 

 of this complex prove to be univalent in Acholla, since they divide 

 only in the first mitosis. 



In all previous cases where a dimorphism of the spermatozoa 

 in regard to the number of chromosomes exists, the female has not 

 only received the larger number of chromosomes, but as far as we 

 can judge with the eye, the larger amount of chromatin. While 

 the numerical rule still holds, Acholla seems to give an exception 

 in that the quantity of chromatin which goes to the male-produc- 

 ing pole is greater than that which goes to the female-producing 

 one. I have made a number of measurements in the first and 

 second divisions, and in every case, the large chromosome seems 

 to contain a larger amount of chromatin than the remaining five 

 differential chromosomes. In connection with the question of 

 sex-determination, this point will be discussed further. 



What can be the significance of such a chromosome complex 

 as is present in the first maturation division and in the prophase 

 of this division? In the Phasmidse, Sinety ('01) recorded a 

 coupling of the odd chromosome with one of the ordinary 

 bivalents. McClung ('05) extended this observation to two 

 other families of Orthoptera, the Acridid?e and Locustidae. Wil- 

 son ('07) describes a coupling of the supernumerary chromo- 

 some with one of the idiochromosomes in Mctapodius and sug- 

 gests the possibility that such chromosome couplings may give 



