The Effects of Physical and Chemical Agencies on 

 Lepidoptera. 



{Being a record of experiments made in 1906 and 1907.) 



By H. S. Fremlin, M.R.C.S., F.E.S. Read February i$t/i, 1908. 



I wish again to bring before your notice some experiments that 

 I have made on the pupae of Lepidoptera. 



The only species that I have to speak of this evening are Vanessa 

 urticce and Abraxas grossulariata. 



The total number of pupae experimented with was 2021, of which 

 1 105 were urticce, and 916 were grossulariata. The pupa? were not 

 selected from special batches of larvae, but, as I understand, the 

 larvae were merely collected from any place in which they happen 

 to have occurred in the wild state. 



I received the pupae as soon as possible after their change from 

 larvae, and they were placed in the experimental jars on the day 

 they were received. 



The following are the conditions in which the pupae were placed: 

 Physical. Chemical. 



Nitric acid. 

 Water. Hydrochloric acid. 



Chloride of lime. 

 98 - 4° F. Sulphur. 



Hydrogen sulphide. 

 Bisulphide of carbon. 

 Controls of the above were kept in all cases. 



The pupae were all kept in glass jars on moss litter, into which 

 sticks were placed for the imagines to crawl on when they emerged. 

 The jars were at first covered with tightly-fitting lids, but it was 

 found that these coverings allowed of no evaporation of moisture, 

 and the result was that in some cases moulds grew over both pupae 

 and moss litter so that it was necessary to admit air, and this was 

 done either by sliding the cover off a little, or by replacing it with a 

 covering of muslin. 



The reagents used were kept in an open bottle standing in the moss 

 litter beside the pupae, save in the cases of water and sulphur. In 

 the case of water the moss litter on which the pupae were placed 

 was moistened, and further, a bottle or tube of water was kept in the 

 jar, and by these means the atmosphere in the jar was constantly 

 saturated. 



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