54 Charles Darwin. 



and his notes on this one point were voluminous. 

 When frost came at Bahia Blanca, few small animals 

 were to be found except by digging, the lizards and 

 insects having taken to the earth. Later they re- 

 appeared, and we here have an interesting example 

 of the care and thoroughness which Darwin gave 

 to all his work. In his log-book he writes : " During 

 the first eleven days, whilst nature was dormant, the 

 mean temperature, taken from observations made 

 every two hours on board the Beagle, was 51°; and in 

 the middle of the day the thermometer seldom ranged 

 above 55°. On the eleven succeeding days, in which all 

 living things became so animated, the mean was 58°, 

 and the range in the middle of the day between 

 60-70 °. Here, then, an increase of seven de- 

 grees in mean temperature, but a greater one of 

 extreme heat, was sufficient to awaken the functions 

 of life. At Monte Video, from which we had just 

 before sailed, in the twenty-three days included 

 between the 26th of July and the 19th of August, 

 the mean temperature from 276 observations was 

 58°.4 ; the mean hottest day being 65°. 5, and the 

 coldest 46°. The lowest point to which the ther- 

 mometer fell was 41°. 5, and occasionally in the 

 middle of the day it rose to 69° or 70°. Yet with 

 this high temperature, almost every beetle, several 

 genera of spiders, snails and land-shells, toads and 

 lizards, were all lying torpid beneath stones. But 

 we have seen that at Bahia Blanca, which is four de- 

 grees southward, and therefore a climate only a very 

 little colder, this same temperature, with a rather 

 less extreme heat, was sufficient to awake all orders 



