78 



llio lowcriiii'- of tcraporaturo prodnccd l)v tlio evaporation 

 of waliT at llie fi'oe surf ace of a ])or()ns tube immersed in 

 iee water, lie (>l)serve(l: 1. Tliat <nil.^, exposed to an air 

 t('mi)erature of 0", soon lose their ability to eling- to the 

 ^vall of a glass container, and in 15 minutes they are rigid, 

 but tliey are killed only by a stay of 3 hours at -15°; 

 '2. Thai hccs l)tH'()nie stiff in ;i shoi't linic in the neighbor- 

 hood of zero, and that they die after 'A}, hours at -1.5°; 

 ."). That several coleoptera, as also the adult Bomhyx, 

 are killed in less than one houi- at -4° to -6°; 4. That 

 the mosquito, Culex pipiens, is killed in one hour at -4° ; 

 5. That house flies are killed in 5 minutes at - 12°, in 20 

 minutes at -8° and in 40 minutes at -5°; 6. That the 

 spif/cr, Tegenaria, dies after an exposure of 45 minutes 

 to - 1)°, or of one hour to - 6° ; 7. That the water spider, 

 Argifroneta, suffers no injury at - 5° as long as it does not 

 congeal, but dies in 3 hours at -4° when it is frozen 

 throughout; 8. That the water mite, Hydrachna, dies 

 after half an hour's exposure to -4° when its body is 

 congealed; 9. That, when the larvae of several species of 

 coleoptera were congealed all through at temperatures 

 lower than -6°, they never survived. (Actual internal 

 congelation was ascertained by sectioning the animals) ; 

 10. That some dipteran larvae could sometimes be revived 

 wlien they were taken out of a frozen medium l)ut never 

 when they were themselves frozen; 11. That the cater- 

 pillars of Smerinflius did not survive a lowering of tem- 

 perature to -10°. To summarize: Roeclel, whose work 

 covers most of the groups of arthropoda, never obtained 

 the survival of a com])letely frozen animal, not even in the 

 larval stage; he found that they all die in a range of tem- 

 perature extending to al)out 10° below zero and during 

 times of the order of an hour. 



According to Bachmetjew (1901), death occurs when 

 an insect which has been subcooled to a certain tempera- 

 ture below zero and has congealed, has its temperature 

 lowered a second time to the subcooling point. The low- 

 est subcooling point that he observed was -15.7° and this 



