No. 425-] NOTES AND LITERATURE. 403 



of color aberrations in butterflies. He also suggests that further study 

 of these effects may explain why so many moths are nocturnal, while 

 the butterflies are diurnal. Some experiments on the influence of 

 respiration showed that Deilephila at 29.4° C. atmospheric tempera- 

 ture could raise its body temperature through at least 3° C. by 

 means of breathing alone. 



The second and more important portion of Bachmetjew's paper 

 deals with the vital extremes of temperature. It is divided into two 

 sections, one dealing with the maximum, the other with the minimum 

 temperature. The vital maximum is the highest temperature at which 

 an insect is able to live, f^xperiments on Saturnia pyri showed that 

 the insect becomes very restless at a temperature of about 39° C. 

 and dies when the body reaches a temperature of 46° C. This is 

 also very near the lethal temperature for plants (Sachs and Schultze). 

 This lethal temperature, however, depends on a number of factors. 

 In general, it may be said that if the insect at high temperature first, 

 has not been exhausted, i.e., has been artificially fed ; second, is not 

 desiccated, i.e., is in a sufficiently moist atmosphere ; and third, pre- 

 sents the same conductivity to heat and the same body size for a 

 given species, — its life will depend only on the coagulation or non- 

 coagulation of its body fluids. Hence, the vital maximum is only 

 another expression for the coagulation point of the body fluids. And 

 if one knew the amount of water in the insect's albumins, especially 

 of those albumins essential to life, the question of the vital maximum 

 would resolve itself merely into a determination of the amount of 

 water. 



Bachmetjew's study of the vital minimum, i.e., the lowest tempera- 

 ture at which an insect can live, brought out some startling results. 

 He found from experiments on a great number of insects that 

 different species died at very different temperatures. But his most 

 interesting results refer to the critical point, which is the temperature 

 to which the fluids of the insect may be undercooled before they 

 begin to congeal and then suddenly rise in temperature till the nor- 

 mal congealing point is reached. Bachmetjew points out the resem- 

 blance of this phenomenon to tjie well-known undercooling of water, 

 which can be cooled to — 25° C. without freezing, but at once rises 

 to 0° C. to freeze. Bachmetjew discovered the undercooling of the 

 body fluids of insects by accident in an experiment on Saturnia 

 pyri 9. The insect was cooled to —9.4° C, whereupon within a 

 minute's time the temperature bounded up to — 1.4° C, the normal 

 congealing point of the body fluids, and then remained constant for 



