556 P. W. WHITING 



and that either maturation division may be reductional, depend- 

 ing upon the species or upon the particular chromosome. Wen- 

 rich has shown that a single chromosome may divide reduc- 

 tionally either in the first or in the second maturation division 

 and that this is governed by chance. The possibility of deter- 

 mining this was due to a morphological dissimilarity of the 

 homologues. He concludes, in general, however, (p. 105), ''As 

 to which of the two maturation divisions is equational and 

 which is reductional, no absolute rule can be laid down. The 

 evidence, however, points to the probability that generally 

 chromosomes with terminal spindle fiber attachment are not 

 separated from each other until the second division, while those 

 that have a non-terminal attachment are separated in the first, 

 and that consequently in the former the reduction occurs at the 

 second division, in the latter at the first division." 



In the work on Diptera the term synapsis is used with such a 

 variety of meanings that the whole matter is quite bewildering. 



Lomen ('14) uses the term in what he considers to be Moore's 

 sense to denote a crowding together of the chromatin at the 

 beginning of the growth period. 



Taylor ('14) avoids all trouble by using Haecker's ('11) "word 

 'syndesis' for the conjugation of the chromosomes, and 'syn- 

 izesis' for their clumping together." 



Stevens ('09) considers that "in Culex it is quite certain that 

 parasynapsis occurs in each cell generation of the germ cells in 

 the telophase." She uses the term synapsis to apply to the first 

 spermatocyte metaphase and states that there is here a pro- 

 longed parasynapsis ending with a telosynapsis before the chromo- 

 somes separate. This is clearly a misuse of the term. 



Metz ('14) uses the term synapsis to denote the association 

 of homologues in metaphase and anaphase of diploid mitoses. 

 In a short review ('16) he states that he has found tjiis pairing 

 of homologous chromosomes in all diploid cells of seventy-five 

 species of Diptera, from the lowest to the highest of the order, 

 and beginning in the egg before cleavage is completed. 



Overton ('09) has shown this approximation of homologues in 

 somatic cells of plants and reviews the literature dealing with 

 this matter. 



