78 PHILOSOPHY OF ZOOLOGY. 



may be kept in this condition for several years. No ordinary 

 change of temperature produces any effect upon them, but 

 they speedily revive if plunged in water. Even in their 

 natural haunts, they are often found in this state during 

 the summer season, when there is a continued drought. 

 With the first shower, however, they recover, and move 

 about, and at this time the conchologist ought to be on the 

 alert. 



The Spiders pass the winter season in a dormant state, 

 enclosed in their own webs, and placed in some concealed 

 corner. Like the toi'pid mammalia, they speedily revive 

 when exposed to intense cold, and strive to obtain a more 

 sheltered spot. 



Many insects which are destined to survive the winter 

 months, become regularly torpid by a cold exceeding 40°. 

 The house fly may always be found in the winter season 

 torpid, in some retired corner ; but exposure for a few mi- 

 nutes to the influence of a fire recalls it to activity. Even 

 some of the lepidopterous insects, which have been hatch- 

 ed too late in the season to enable them to perform the bu- 

 siness of procreation, possess the faculty of becoming tor- 

 pid during the winter, and thus have their life prolong- 

 ed beyond the ordinary period. These insects can all 

 be preserved from becoming torpid by being placed in 

 an agreeable temperature, as the following experiments 

 of Mr GouGH (Nicholson's Journal^ vol, xix.) testi- 

 fy. In speaking of the Hearth Cricket, {Gryllus do7ncs- 

 ticus), he says, " Those who have attended to the manners 

 of this familiar insect will know that it passes the hottest 

 part of the summer in sunny situations, concealed in the 

 crevices of walls and heaps of rubbish. It quits its sum- 

 mer abode about the end of August, and fixes its residence 

 by the fireside of the kitchen or cottage ; where it multi- 

 plies its species, and is as merry at Christmas as other in- 



