NOTKS. 427 



while its body temperature, according to the figures he was so good as 

 to conununicate to me, was never more than a few degrees higher than 

 the air. 



Note 37, page 112. It is a fact that frogs often deposit their spawn in 

 water hardly above the freezing-point, and a vast number of inverte- 

 brate creatures live in equally cold water. These same individuals, 

 however, do not perish when even their body temperature is raised in 

 the summer to more than 30° or even 40°. How far they suffer from 

 it is, however, not established. 



Nate 38, page 114. An enumeration of the observed or reported cases 

 of the resuscitation of wholly frozen animals is to be found in Schmarda's 

 Thiergeograpliie, i. pp. 8 and 98. Insects, fishes, toads. Actinia, 

 Crustacea, Mollusca, and Nematoda figure in this Kst. It is well known 

 that fish can be conveyed in ice, or even quite frozen up, and revive on 

 being thawed again ; but in all these cases the thawing must be very 

 slow and gradual ; if it is too rapid the creature dies. Plants exhibit the 

 same characters. 



Nate ^9, page 116. It is difficult — in some cases quite impossible— to 

 decide whether the data given are to be depended upon or not ; isolated 

 and incidentally made observations are often made to serve as evidence 

 for general statements. Thus it has been said that the Arctic fox is white 

 in vidnter, and in summer of various colours ; but Payne says this is in- 

 accurate, and that Canig lagopus may be found white, blue, or grey at 

 all seasons of the year. 



Nate 40, page 117. Weissmann succeeded in transforming all the 

 individuals of a summer brood of Picns Napi to the winter-form by 

 maintaining a low temperature. With reference to Weissmann's estimate 

 of the facts communicated by him as to the rearing of Vanessa levana- 

 prai'sa, I must observe that I cannot agree with him ; interesting as his 

 researches are, they do not seem to me either to have been carried out 

 systematically enough to allow of the deduction of any definite con- 

 clusion, nor to prove that the speculations propounded by him are 

 thoroughly well founded. 



Nate 41, page 119. ' Assimilation in plants is only possible between 

 a specific minimum and maximum of temperature ; between these two 

 extremes lies an optimum for the development of the species.' So 

 says Pfeffer, and this shows that the same law obtains for plants as for 

 animals. Unfortunately we cannot assert that we have ascertained the 

 curves of temperature for animals, as botanists have already done for 

 many plants. This, it is true, results in great measure from the diffi- 

 culties offered in experimenting on animals ; the phenomena of life 

 are far more complicated in them than in plants, they grow much more 

 slowly and at the same time are far less easy to measure and to confine. 

 However, there are a number of rapidly-growing cold-blooded aquatic 

 animals (water-snails, Naidise, Branchipus, Apus, &c.) which are not 



