2 CAPT. C. r. U. MEEK ON THE 



Gryllotalpa led him to assert that the first maturation division is longitudinal, 

 the second being transverse and reductional ; and McClung's paper upon 

 Bippiscus in 1899 has corroborated this view. Further evidence in support 

 of the theory o£ Post-reduction has since been supplied by the work of 

 Sutton upon Brachystola magna, and by the more recent investigations 

 of Nadine Nowlin and Robertson upon Melanoplus bivittatus and Sijrhula 

 admirabilis respectively. On the other hand, de Sinety, in a paper upon the 

 Phasmidse, has declared that both maturation divisions in the Orthoptera are 

 longitudinal and equational. In 1905 Montgomery, writing on Syrhula, and 

 Farmer and Moore, writing on Periplaneta, upheld the theory of Pre- 

 reduction ; and this view has since been adopted by Davis in a paper upon the 

 Acrididge and Locustidee, and by Gerard in a paper upon Stenobothrus bigiittuhis. 

 The studies of Sutton upon Bi^acliystola magna led to certain discoveries 

 with regard to the chromosomes themselves : firstly, he found that they 

 exhibited a remarkable degree of isolation, for each became enclosed in a 

 distinct vesicle during the telophase of the secondary spermatogonial mitosis. 

 These vesicles fused later at one polar extremity, with one exception to which 

 I shall allude. Since the chromosomes remain in compartments during 

 resolution into spiremes, he has concluded that their individuality is never 

 lost, and that they are morphologicall}^ independent units : this phenomenon 

 has been observed by Otte in Lucusta viridissima, but is apparently confined 

 to a small number of organisms. The nucleus at this stage usually exhibits 

 a long, continuous, and highly convoluted spireme, or even a complete 

 reticulum, formed by the combined resolution of the chromatin filaments ; 

 Grerard describes this condition in Stenobothrus biguttulus, in which he finds 

 no trace of separate vesicles. 



Sutton further discovered in Brachystola that the chromosomes of the 

 spermatogonial complex invariably show certain size and shape relationships, 

 and that, with one exception, they can be arranged in a graduated series of, 

 pairs : this has since been corroborated in other types by the work of 

 Baumgartner, Davis, Gerard, McClung, Montgomery, Nowlin, Robertson, 

 the Schreiners, Stevens, and Wilson, He found moreover that these 

 relationships persist in the later spermatocytes, and, since the number of 

 chromatin bodies is halved at this stage, concluded that a conjugation of 

 members of the spermatogonial pairs had occurred during the intervening 

 period. This view is now held by the majority of cytologists ; and Otte says 

 that he has actually witnessed a side to side conjugation of chromosomes in 

 Locusta. Bonnevie, Sainmont, Wilson, and von Winiwarter carry the theory 

 even further, for they believe that there is complete fusion of the associated 

 chromosomes during this period of lateral juxtaposition ; on the other hand, 

 the entire theory of conjugation is denied by Duesberg, Fick, Gerard, and 

 Meves. 



This theory has been eagerly seized by Meudelians to explain the 



