394 BOWEN. 



lobes consecutively, reckoning the first on that side toward which the 

 efferent duct opens as lobe 1, lobe 2 the next, and so on, as indicated in 

 Text-figures 1/1, B and C. In certain special cases, e.g., Stiretnis 

 (Text-fig. ID) this plan can not be rigorously applied, and in such 

 cases, a more or less arbitrary numbering must, of course, be adopted.* 



In 1898 Montgomery called attention for the first time to the fact 

 that in Evsckistus (probably tristicjmus and another species (Mont- 

 gomery '10), though both were referred originally to Pcntatoma and 

 Tropicoris) lobes 4 and 6 of the testis were characterized by the con- 

 stant possession of spermatocytes unusually large as contrasted to 

 those of lobes 1, 2, 3 and 5. In lobe 1, the spermatocytes averaged 

 slightly smaller than in those of lobes 2, 3 and 5, but the difference was 

 not considered significant. The structure of all the spermatozoa was 

 stated to be the same, though differences in size were inferred. This 

 peculiar polymorphism is not due to any of the known nuclear de- 

 rangem.ents, in fact the cells in all lobes are identical up to the synaptic 

 period. As the spermatocytes enter the growth period, however, the 

 nucleus and cytoplasm of those in lobes 4 and 6 increase in size very 

 much more than the others, resulting in characteristically "large" 

 generations. Nevertheless, in the reduction divisions all the chromo- 

 some plates are identical in composition and corresponding chromo- 

 somes are of exactly the same size regardless of the disproportion in the 

 sizes of the cells themselves. Montgomery was disposed to attribute 

 the greater size of the cells in lobes 4 and 6 to nutritional dift"erences 

 traceable to the blood supplies. He also noted some specific differ- 

 ences in the cytoplasmic structures to which reference will be made 

 elsewhere. 



In 1910, ]\Iontgomery published a paper dealing in part with this 

 unusual "dimegaly," — as he now termed it,^ — including observations 

 on the mature sperm and further notes of a general nature. In this 

 paper he repeated his former statements as to the size relationships, 

 but now reported that in lobe 5 the spermatocytes were constantly 

 smaller ^ than in lobes 1, 2 and 3. No reference was made to his 



reverse of mine. Some systematic method of orientation is, however, essen- 

 tial in examining many different species, and as the sperm duct is a constant 

 landmark 1 have found it convenient to number the lobes in relation to it. I 

 shall express Montgomery's findings in my own system of numbering, a fact to 

 be remembered in comparing with his original reports. 



4 For other details of the structure of an hemipteran (Euschistus) testis, 

 reference may be made to Montgomery's papers, especially that of 1898. 



5 I shall refer to the three sizes of cells as (1) large or unusually large, (2) 

 normal or small, and (3) smallest or unusually small. 



