368 



SCIENCE 



[N. S. Vol. XXXVIII. No. 976= 



this year over 325 individual parasites have 

 been bred out. The length of the life cycle has 

 been found to vary from ten to eighteen days, 

 depending on the climatic conditions. 



The parasite has been found in every wheat 

 and corn field examined around Manhattan. 

 Of 3,101 eggs collected between April 28 and 

 June 10, the average per cent, of parasitism 

 was 20.8, and of 116 eggs collected at Crawford 

 (central Kansas) the per cent, of parasitism 

 was 16.3. The insect has also been taken at 

 Dodge City (southwestern Kansas). 



The work is still under way and a full 

 description of the parasite together with notes 

 on its life history and efficiency will be pub- 

 lished later. 



Mr. A. B. Gahan, entomological assistant of 

 the Bureau of Entomology, U. S. Dept. of 

 Agric, to whom specimens of the parasite were 

 sent for determination, says : 



I have made a partial examination of these 

 parasites and find them to belong to the family 

 Proctotrypidce, and they probably fall close to the 

 genus Telenomus. It will require further study 

 for me to determine definitely regarding them. 

 It seems probable that they represent not only a 

 new species, but possibly a new genus. 



In a more recent letter Mr. Gahan writes : 



After exhausting every effort to determine the 

 parasites of the chinch bug which you sent me 

 and failing to find any such species described, I 

 turned the specimens over to Mr. J. C. Crawford, 

 of the United States National Museum, to see what 

 he could do with them. He informed me yester- 

 day that he had arrived at the same conclusion as 

 myself, namely, that the species would require a 

 new genus. 



James W. McColloch 



Kansas State Agricultural College 

 AND Experiment Station 



SOME observations on the sexuality of 



SPIEOGYRA 



The gametes of Spirogyra are described in 

 the text-books of botany as being morpholog- 

 ically alike. A few workers have claimed that 

 the female gametes in certain species are 

 larger than the male. Aside from these observa- 

 tions the writer knows of no published accounts 

 of attempts to point out other differences be- 



tween the male and female gametes of Spiro- 

 gyra. A large number of measurements of 

 the conjugating cells have been made by the 

 writer, but no constant difference in their size- 

 has been found. Several examples were ob- 

 served where the transverse diameter of the 

 filaments producing male gametes was slightly 

 less than that of those in which the females 

 were formed. The male cells may be longer 

 or shorter than or equal the length of the- 

 females. The cells of any one filament vary in 

 length. It is, therefore, quite evident that 

 the gametes of some Spirogyras can not be dis- 

 tinguished as male and female on the basis of 

 their relative size. 



The writer observed a few years ago that the 

 chloroplasts of the female gametes of Spiro- 

 gyra crassa, just after the formation of the- 

 conjugating tubes, contained a much larger 

 amount of starch and more pyrenoids than 

 those of the male. The pyrenoids of the male 

 gametes were larger and the amount of starch 

 surrounding each pyrenoid was considerably 

 less than in the females. Practically the 

 same kind of differences seen in the gametes of 

 Spirogyra crassa were observed in three other 

 undetermined species of Spirogyra. By care- 

 ful fixation of material of these unidentified 

 species, taken just before or immediately after- 

 conjugation had begun and staining in iron- 

 hemotoxylin and erythrosin, the cytoplasm of 

 the majority of the female gametes stained a 

 little more darkly than that of the males. The 

 density of the staining of the female gametes- 

 was so marked in some filaments that they 

 could easily be distinguished from the male 

 even when the two were not in close proximity. 

 No examples of conjugating cells were found' 

 where the male gamete stained more darkly 

 or in which there were more starch and pyre- 

 noids than in the female. Every year during 

 the past seven years, the writer has examined' 

 several hundred filaments of Spirogyra in 

 which conjugation was occurring or had just 

 taken place, and in every example, the gamete 

 with less starch and pyrenoids was passing 

 over to or had just united with the gamete pos- 

 sessing a greater amount of starch and pyre- 

 noids. The protoplasts of any one filament 



