39 



generally known that those animals which were subject to 

 either hibernation or aestivation appeared to retire at intervals 

 during their active life for a shorter sleep of, say, a couple or 

 more days. Dormice did this, as did the hedgehogs, and pro- 

 bably many insects did the same. This habit was known as 

 diurnation, or day-sleep, and appeared to be little understood. 

 It must not be confounded with the retirement of land-shelled 

 molluscs for the growth of the shell covering, as was their 

 custom. In the vegetable world each of these periods of rest 

 occurred. Most seeds either hibernated or activated, as did 

 trees, by losing their leaves and by the downflow of the sap. To 

 what extent seeds might be affected was doubtful ; but there 

 was no doubt vegetable life might be kept in abeyance for 

 long periods by prolonging the condition of hibernation arti- 

 ficially. The pupae of insects often laid over in that stage of 

 their existence for three, four, or more years, thus hibernating 

 the whole time as it were. This might to some extent account 

 for special seasons of exceptional abundance and consequent 

 destruction of vegetation by these unwelcome guests, which had 

 only been remaining in reserve in one stage or other of their 

 metamorphosis until a favourable event caused their emerg- 

 ence in abundance. 



FEBRUARY 24th, 1887. 



R. ADKIN, Esq., F.E.S., President, in the Chair. 



Mr. J. E. Kelsall, Mr. J. Lee, and Mr. E. B. Nevinson 

 were elected members. 



Mr. Tutt exhibited long series of Tephrosia crepuscularia. 

 Hb., from Hungary, and remarked that he was unable to 

 obtain any forms of T. biundnlaria, Bork., from that country, 

 although he had received it from Germany. Mr. Tutt further 

 showed specimens of Continental Agrotidcz, and, for the pur- 

 pose of comparison, British forms of the same species. Also 

 Continental Acidalia perochraria, Fisch., which he stated 

 appeared in the British list of Lepidoptera, but on what 

 authority he did not know. To him the specimens exhibited 

 looked like intense forms of A. ochrata, Scop. 



