258 The Ohio Naturalist. [\ ol. VIII, No. 4, 



parthenogenesis from a definitive cell in the formation of which 

 the two polars alone are concerned; or even possibly from a 

 single polar cell. The lack of fusion of the polars, if such con- 

 dition exists, may represent either a primitive condition or a 

 more recent, parthenogenetic condition. Theoretically, there- 

 fore, it is possible to have an "x" endosperm generation of two 

 different origins, a "2x" endosperm generation of two types 

 differing in constitutional structure, and a "3x" endosperm 

 generation, but none of these could properly be called an embryo. 



Botanical Garden, Univ. of Zurich, Nov. 25, 1907. 



SOME OBSERVATIONS CONCERNING THE EFFECTS OF 

 FREEZING ON INSECT LARVAE.* 



James S. Hine. 



It has been known for a long time that some insect larvae can 

 withstand low temperatures without being noticeably injured 

 thereby. Also that there is great difference among species of 

 insects, or in some cases even among the individuals of a single 

 species, in regard to the minimum temperature at which life is 

 endangered. Economic entomologists have now and then 

 made the claim that frosts, especially when they occurred at 

 certain seasons, have been important factors in the control of 

 injurious species. 



In 1893 while studying the life history and habits of a moth, 

 Bellura obliqua, which passes its larval stage in the stems of the 

 cat-tail reed, Typha latifolia, I had an opportunity to make 

 some observations on larvae of this species which are normally 

 found in the reeds throughout the winter. The winter was 

 rather severe for the latitude of Columbus where the observations 

 were made, and from January 10 to January 20, the temperature 

 dropped below zero every night, varying from —2 Fahr. on the 

 10th, to -17 on the 17th. Large numbers of the larvae were 

 collected during this interval, some during each day, and with 

 the specimens some tests were made. Three larvae collected on 

 the 14th, were placed in water and placed outside on a porch roof 

 during 12 hours the following night when the minimum tem- 

 perature recorded was -15. The next morning the specimens 

 were brought inside and thawed out, after which they were 

 taken from the water and kept in a tin box at the temperature of 

 a living room for about 12 hours. These same larvae received 

 the same treatment for six consecutive nights and days, during 

 the time withstanding a minimum temperature of -11 on the 



* Read before the Ohio Academy of Science, Nov. 30, 1907. 



