SUPERNUMERARY CHROMOSOMES IN DIABROTICA. 



punctata in October, 1907, I found more than two males to one 

 female, in one lot 58 males to 25 females. In 1909 the number 

 of males and females was noted for each lot dissected. Between 

 July lo and August 12, 107 males and 102 females were counted 

 in random collections from two neighboring gardens, but it was 

 noticed that the latios in the two garden- were quite different. 

 In garden A there were 58 males to 26 females; in garden B, 

 4<> males to 76 females. A second lot from garden A collected 

 betueeii August 21 and September 15 gave 101 male- to 24 

 female-. The percentage of females in garden .1. first lot. was 

 30.9, -ecnnd lot 19.2, average 23.9, and for garden B 60.8. 

 At I ..i Jll.i in 1910 the ratios ran more evenly. 



cf 9 



la, June 17 and 18 



ioii.il < iiy. June 22 



I a Julia. June 28 14 



l"ll.i. July i i; 



I ..i J"ll.i. July 4 



ig 



i j i 



Ai Moiini.iin View again the ratios were peculiar. I i\- 

 rand' mi < - -llertions in Garden A gave loo male- to jo tnnale-, and 

 i\\o oilier later collections 76 males to 18 female-. ( >nl\ a few 

 \\i M . ollrcted from garden B giving 12 male-, to d female-.. In 

 i<n i mixed lots from both gardens gave more male- than female-. 

 (I 147. These were recorded incidentally while fixing a lot of 

 testes lor sections. By referring to the table on p.rj< 232, it will 

 be seen that the numbei of supernumeraries run- about the -aim- 

 for the lir-t 100 in 1909, about one half of which came from each 

 warden .1 51 and B 49), and for the second ion, .ill of which 

 came from garden .-1. It therefore seems unlikely that the -nper- 

 mimcrarie- have anything to do with the dineivn. . in sex ratio- 

 iu the t\\o gardens. The soil in garden .1 is harder in -nmmer 

 more adobe in it and less thoroughly cultivated than B. T\\<- 

 possibilities are suggested in this connection: (a) The male- may 

 be more successful in pupating and e-c.iping from the hard -oil 

 than the females or (b) few of either sex may emerge from the 

 hard -nil in garden A, and the males may be better livers and 

 so come in larger numbers from other neighboring gardens. The 

 latter i- re-aided as more probable. 



