SYNAPSIS AND CHROMOSOME ORGANIZATION 473 



been presented by Robertson ('16). In many respects the evi- 

 dence and conclusions which have been independently reached 

 by Robertson and myself will be mutually corroborative. In 

 regard to some points, however, differences of interpretation 

 exist which will be discussed in an appropriate place. 



In view of the very interesting conditions in Trimerotropis 

 and Circotettix, where telomitic chromosomes are paired with 

 atelomitic ones, as found by Dr. E. Eleanor Carothers ('17) 

 it seemed worth while to examine stages which would indicate 

 what form of synapsis occurs between these chromosomes of 

 diverse form. Dr. Carothers very kindly permitted the use of 

 her slides for this purpose. It may be stated at once that para- 

 synapsis was found to occur for all the chromosomes of Trimer- 

 otropis of whatever form, just as it does in Chorthippus and 

 Phrynotettix. In addition to the subject of synapsis the topics 

 of pre- and post-reduction and chromosome organization will 

 be considered. 



In this paper new terms will be used in accordance with those 

 recently adopted by Dr. Carothers ('17), as follows:(l) Telomitic — - 

 chromosome with terminal fiber-attachment, i.e., rod-shaped; 

 telomitic and rod-shaped will therefore be used interchange- 

 ably; (2) atelomitic — chromosome with non-terminal fiber-attach- 

 ment = V-shaped; V-shaped and atelomitic will be used inter- 

 changeably; (3) heteromorphic — those pairs of chromosomes (tet- 

 rads) of which one member is telomitic and the other atelomitic, 

 or, of which one member is noticeably different in form or size 

 from its mate; (4) chromomere-vesicle — ^the plasmosome-like ap- 

 pendages formerly called 'vesicles' by Carothers ('13), and called 

 appendages and plasmosome-like structures by the writer ('16). 

 I shall also make use of McClung's ('14) term, euchromosome as 

 equivalent to Montgomery's 'autosome.' 



All drawings have been outlined with a pencil under the 

 camera lucida and then inked while the cell remained under 

 observation. 



