RESEARCH SEMINAR. 235 



(Bucephalus Jiaiincanns] in the oyster ; that the cercariae becom- 

 ing mature* leave the oyster and swim about in the water ; that 

 they are from thence obtained as food by the silverside and 

 other small fish ; that in these fish they encyst, finally to be 

 released, and become sexually mature when their hosts are eaten 

 by Tylositriis. 



The extent of infection, the character of the regions in which 

 infected oysters are found, the effect of the parasite upon the 

 oyster, the origin of the germ cells from which the cercarise 

 arise and the significance of the differences in appearance and rate 

 of growth in the experiment fish were also mentioned. 



The experiments described were conducted at the Beaufort, 

 N. C., Fisheries Laboratory. 



19. Relation of Ants to Temperature and Submergence. 



By ADELE M. FIELD. 



An artificial nest was made, having as its basis a half-cylin- 

 der of copper, with ends projecting beyond the nest. One end 

 of the copper was heated by an alcohol flame, while the 

 other end was surrounded by ice. Different parts of the nest 

 presented diverse temperatures, ranging from 10 C. or 14 F. 

 to 60 C. or 140 F. Ants of various species were introduced 

 into this nest, and it was found that the temperature preferred by 

 them was from 24 C. or 76 F. to 27 C. or 82 F. Below 

 15 C. or 60 F. the ants become sluggish, and increase of 

 temperature was accompanied by increase of activity. Above 

 30 C. or 86 F. they manifested discomfort or distress. Expos- 

 ure to heat so great as 50 C. or 122 F. for a period of fifteen 

 seconds for the smaller ants, or of two minutes for the larger 

 ants, invariably killed them, probably by coagulation of their 

 protoplasm. The effect was the same whether the heat was 

 applied through a wet or dry medium. 



Ants of the same species as those killed by heat, survived 

 submergence in cool water for seventy-two hours. The futility 

 of ploughing up ant-nests with the expectation that the spring 

 rains would destroy the ants was alluded to, and the application 

 of heat was suggested as a better means of destroying these pests 

 on farms. 



