682 C. E. McCLUNG 



size and form. By end to end synapsis these 20 chromosomes 

 become reduced to 10, am.ong which the heterochromosomes 

 are indistinguishable from the tetrads. There is a persistent 

 chromosome individuahty manifested. (2) The various forms 

 of prophase chromosomes reported by other cytologists appear, 

 according to Montgomery, but X's are rare. Rings are not un- 

 common at this stage. (3) Forms of chromosomes recognizable 

 in the prophase may appear in the metaphase of the first sperma- 

 tocyte, but such forms as rings, common in the prophase, are 

 rare in the metaphase. Whatever the form, however, a common 

 type is recognizable, i.e., two spermatogonia! chromosomes united 

 end to end and having fibers attached to the opposite ends. (4) 

 In the mid period of mitosis the chromosomes take up such a 

 position that the fused ends lie in the equatorial plate. Rings 

 are found only exceptionally, as are X's. (5) The first matura- 

 tion division sees only a separation of whole, univalent spermat- 

 ogonial chromosomes. Such as lie extended in the equatorial 

 plate are pulled past each other to an opposite pole of the spindle. 

 (6) Fiber attachment is at the ends of the chromosomes opposite 

 the synaptic fusion. (7) In the anaphase the chromosomes all have 

 the form of V's in which the enclosed space represents the earlier 

 longitudinal split.' (8) A reduction division of all the chromo- 

 somes is accomplished in the first spermatocyte where the hetero- 

 chromosomes behave as do the other tetrads. (9) Also in the 

 second sperm.atocyte all the chromosomes divide in the same 

 way, so that a mere equation division results. This includes the 

 heterochromosomes. 



Davis ('08) has made a careful and extended study of a number 

 of Acrididae and Locustidae and finds a conunon type of matura- 

 tion processes in all. For the Acrididae he chooses, as representa- 

 tive, the conditions found in Dissosteira, and includes also a con- 

 sideration of Stenobothrus. For the Locustidae Steiroxys is 

 employed. From this diverse material he concludes that (1) 

 the spermatogonia! chromosomes may be recognized in pairs, 

 with the exception of the accessory chromosome, and these reap- 

 pear in the first spermatocyte, joined end to end, to form the tet- 

 rads. (2) Chromosomes of the first spermatocyte are all of the 



