184 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Verhoeff specially questions the statement that cave animals are blind 

 as an adaptation to their habitat ; he believes that, at least frequently, 

 the cave animals are of low organisation, and the blindness is a primitive 

 character. Absolon does not believe that the cave animals are less 

 highly organised than the surface forms, and finds that they are very 

 sensitive to light, and rapidly die when exposed to its influence. He 

 believes that this proves that even where eyes are present they have lost 

 their prime function. Again, Absolon declares himself unable to perceive 

 the cogency of Verhoeff's reasoning in regard to the apparently ano- 

 malous distribution of Brachydesmus subterraneus ; to him this distribu- 

 tion appears to afford a strong argument in favour of the existence of 

 a true subterranean fauna. Further, in Moravia a cave which had not 

 had any communication, direct or indirect, with the exterior for many 

 centuries, was found on its discovery to possess the typical Moravian 

 cave fauna. 



In another communication * Absolon pursues the argument from 

 the wide distribution of the cave fauna. The animals must be supposed 

 to have originally reached the caves either actively, by their own move- 

 ments, or passively by floods or as parasites, ivc. Their subterranean 

 distribution would thus depend upon their distribution, past or present, 

 above ground. Thus Lipura stillicidii only occurs in caves, and occurs in 

 such widely separated localities as Ireland, Oarniola, and Moravia ; it 

 must be supposed to have had a former surface distribution over the 

 whole of Central Europe, from Ireland to the Danube. 



Again, other things being equal, the fauna of the caves of a district 

 will depend upon the surface fauna of the district ; hence the abundance 

 of Thysanura and Acarids in Moravian caves, for these groups are 

 specially abundant in Moravia generally. As the modification of sur- 

 face forms into cave forms is still going on, there are many subterranean 

 forms which also live at the surface, though often in diminished numbers. 

 The author believes however that the Moravian cave fauna has been in 

 existence since the deposition of the diluvium ; for the Slouper cave, which 

 he believes was entirely closed from that period till its opening in 1890. 

 contained the typical fauna. 



Eyes of Cave Salamander.f — Prof. C. H. Eigenmann and Mr. W. A. 

 Denny have obtained larvae and adults of Typhlotriton spelseus, and find 

 that in the larvae the retina closely resembles that of Amblystoma, all 

 the layers being well developed, but in the adult the rods and cones 

 and outer molecular layer appear to be absent. 



Temperature of Fowls.* — Dr. Ch. Fere has made observations on 

 this with some interesting results. Hunter put it at 39 • 4-10° C, Davy at 

 42* 2-43 '9°, Prevost and Dumas at 41 "5°, anl there have been other 

 estimates not less diverse. Fere made observations on birds which were 

 accustomed to be handled. 



The most frequent figure is 41° and a fraction, but the temperature 

 rises with excitement, falls in hypnosis, and also during incubation, 

 approximating somewhat towards that (38-39°), which is most favourable 



* Op. cit., xxiii. (1900) pp. 57-60. t Proc. Indiana Acad. Sci., 1898, pp. 252-3. 

 X Journ. Anat. Physiol., xxsv. (1899) pp. 80S-16 (9 tracings). 



