288 Mr. 0. H. Latter on thr s^'crction of 



I. TJie softening of the cocoon. 



A nnml)er of piipse were cut out from their cocoons, 

 and enclofied in red litmns-paper in such a way as to 

 compel the moths to pierce the paper in order to effect 

 their escape. In each case the papers were moistened 

 by the emerging imago with a fluid which produced a 

 deep blue stain of varying dimensions. The alkalinity 

 of the fluid was thus proved. These stained papers were 

 useless for analysis owing to the impurities present in 

 the litmus-papers. Accordingly some forty pupae were 

 enveloped in best Swedish filter- japer, which is entirely 

 free from all impurities, and contains no substances 

 soluble in water. There was a slight difficulty in 

 arranging the paper so as to afford sufficient obstruction 

 to the emerging imago. Double thickness of the paper 

 was too much for the imago to penetrate, and a single 

 thickness not sufficient to provoke the maximum dis- 

 charge of the softening fluid. About ten pup?e were 

 enclosed in glass tul)es, with their heads against the 

 closed ends. The majority of the pupae emerged success- 

 fully from the papers, yielding me thirty-two papers, 

 each stained very faintly by the ejected fluid. The 

 pupae in glass tubes did not succeed so well — only four 

 hatched (one is still alive, and evidently going over to 

 next year), and of these only one was of any use: the 

 fluid in the other three cases being spoiled by mixture 

 with excrementitious matter. The one tube I was able to 

 make use of contained a few drops of clear watery liquid. 

 This tube I obtained in a satisfactory condition by fortu- 

 nately seeing the imago just struggling to get free. I 

 accordingly waited till I judged that most of the fluid 

 was ejected, and then withdrew the moth and pupa-case 

 from the tube with a pair of fine forceps. 



I then proceeded to analyse the stains on the papers. 

 All stains of excrement were carefully cut away, and 

 only absolutely pure stains were retained. These were 

 placed in distilled water, and raised to a temperature of 

 about 90° C. ; at the same time the papers were kept in 

 motion by stirring them with a glass rod, so as to reduce 

 them to pulp. I then filtered off" the licpiid, and con- 

 densed it by evaporation at about the same temperature. 

 When cool, analysis yielded the following results : — (1) 

 The fluid was decidedly alkaline; (2) there was iDresent 



