154 SUMMARY OF CURRENT RESEARCHES RELATING TO 



c. General. 



Animal Fats.* — C. Schneider and S. Blumenfeld have made a 

 chemical study of the fats of seals, porpoises, bears, otters, etc. It 

 appears that seals from the coasts have more iodine in their fat than 

 those from the open sea ; that the otter has much more iodine in its fat 

 than a terrestrial carnivore like the wild cat ; and that, in general, there 

 is more iodine in the superficial fat than in the internal fat. 



Volant Adaptation in Vertebrates.! ^R. S. Lull concludes that 

 volant adapttition has occurred seventeen times among Vertebrates, ten 

 of which {Rhacophorus, Ptychozoon, Draco, Petauroides, Petauras, JEro- 

 bates, Anomalurns, Pteromys, GaleopitMcas, and Propithecvs) are merely 

 adaptations for more or less prolonged " soaring " leaps, while in seven 

 instances (Thoracoptenis, Gigautopterm, Exocwtus, Dactyloptenis, Ptero- 

 saurs, Birds, and Chiroptera) true flight has been developed — a little 

 doubtfully in some cases. 



Soaring implies, witli but one exception, the development of a fold 

 of skin along the animal's flanks, supported in one instance {Draro) by 

 an extension of the ribs beyond the body-wall, but generally stretched 

 between the fore and hind limbs. This fold is often supplemented by 

 others in front of the fore limbs and between the hind limbs, sometimes 

 involving the tail. 



True flight always implies a more or less profound modification of 

 the fore limbs, which Ijecome, as a consequence, unsuited for ordinary 

 progression. True flight has been developed once in each of the classes 

 of strictly air-breathing animals, and probably at least four times among 

 fishes. 



Except in fishes, soaring implies also present or ancestral arboreal 

 adaptations, and this may apply as well to the true fliers. It is certainly 

 true of the bats, possibly true of the birds, but of the Pterodactyls one 

 cannot be certain. 



Besides the primary mollifications which constitute the machinery of 

 flight, other portions of the body, especially the nervous system, the 

 sensory and nutritive organs, may exhibit secondary volant characteristics. 

 These, like the primary modifications, are in direct proportion to the 

 powers of flight. 



The Labyrinth of Mammals and Birds. J — A. A. Gray describes 

 this organ in tlie lion, the Indian gazelle, the three-toed sloth, the 

 kangaroo, the crested screamer, and the ostrich. Some observations are 

 made upon the conditions of the inner ear in Mammals in general. In 

 addition to the peculiar type found in Monotremes, the cochlea occurs in 

 a sharply pointed form, e.g. in Carnivora and Rodents, and in a flattened 

 condition as in man, monkeys, lemurs. Ungulates, and Cetacea. As 

 regards the perilymphatic space, it is usually either very small or com- 

 pletely absent in the canals. Man, monkeys, and the seal are exceptions 

 to this rule. This space does not appear to have any physiological 



* Chemiker Zeitung, xxx. (1906) No. 6, 6 pp. See also Zool. Zentralbl., xiii. 

 (1906) p. 702. t Amer. Naturalist, xl. (1906) pp. 537-66 (14 figs.). 



X Proc. Roy See. London, Series B, lxxviii.,No. B 525 (1906) pp. 284-96 (3 pis.) 



