August 21, 1914] 



SCIENCE 



279 



Special consideration is given to what the 

 author terms the soarability of air, the condi- 

 tion that enables it to furnish energy for soar- 

 ing flight, and the state of the weather as to 

 sun, shade, wind, heat or cold are carefully re- 

 corded, as well as the time of day at which 

 birds begin to soar. Soarability is believed to 

 be brought about either by the sun or the wind, 

 and sun soarability is stated to occur at a 

 fairly definite time of day, varying naturally 

 with the season. Here we are reminded of 

 Mouillard's observations on griffon vultures in 

 Algeria and his similar statement that they do 

 not begin to sail until the sun is well above 

 the horizon. The author seems inclined to 

 have at first considered that there was a direct 

 connection between heat eddies, indicating 

 rising currents of air, and soarability, but 

 later decided that this was not the case. And 

 yet the curve showing time of appearance of 

 heat eddies for a month coincides absolutely 

 with the time of sun soarability. 



Headers may recall, though Dr. Hankin 

 does not mention it, the theory that soaring is 

 effected by ascending currents of air imping- 

 ing on the curved, though very minute, bar- 

 bules of feathers. Wind soarability is believed 

 to be due to some inherent property of the air 

 and not to mere velocity, and throughout the 

 book one notes the author's evident feeling 

 that birds, flying fishes and dragon flies obtain 

 energy from the air in some occult, or at least 

 unknown way. Occult it does seem, to any 

 one who has watched an albatross gliding into 

 the eye of the wind or tacking back and forth, 

 perfectly at ease in a driving gale. Wonderful 

 it certainly is in view of the infinitesimal ex- 

 penditure of muscular energy, but, remember- 

 ing Langley's memoirs on the internal work 

 •of the wind and the strong and varied eddies 

 that he showed might be present in an appar- 

 ently steady breeze, one feels that birds with 

 their thousands of years of experience and 

 automatic adjustment to every 'air current can 

 derive sailing energy from, to us, invisible 

 sources. 



Great attention is paid to the use of the 

 wings and tail, and careful records are given 

 of their varied motions, positions and relative 



angles to the. body in directing, accelera- 

 ting or checking flight; all of which are most 

 valuable. 



An extremely interesting chapter is devoted 

 to the Flight of Flying Fishes, containing 

 carefully-made and well-recorded observations 

 of the character of their flight and the condi- 

 tions under which it is made. The conclusion 

 reached is the same as that of Colonel Durn- 

 ford, that they do actually fly, and that initial 

 impulse is utterly inadequate to account for 

 the long distances covered, the sustained speed 

 and ability to change direction when on the 

 wing. 



We are introduced to a considerable number 

 of new words, or new meanings, such as soar- 

 ability, flex-gliding, tail-jolting, and while at 

 first sight these seemed unnecessary, yet on 

 further perusal one was forced to admit that 

 they conduced to brevity and clarity of state- 

 ment. Lexicographers will find these new words 

 and terms carefully defined in a glossary and 

 will duly thank Dr. Hankin for his thoughtful- 

 ness and commend it to future coiners of 

 words. F. A. L. 



BECENT STUDIES IN ANIMAL PIGMENTA- 

 TION 



Much has been written on animal pigmen- 

 tation from both the biological and the chem- 

 ical standpoint, but the views regarding the 

 nature and origin of pigment are still at vari- 

 ance. Perhaps the chemists have made most 

 progress in determining the chemical nature 

 and composition of animal pigment, especially 

 of that form known under the name of melanin, 

 which occurs either normally or pathologically 

 in the animal body, hair or feathers. Dr. 

 Eoss A. Gortner, of the Cold Spring Harbor 

 Station for Experimental Evolution, who has 

 devoted a number of years to this subject, 

 states that the black humic substances, known 

 as artificial melanin or "melanotic sub- 

 stances," resulting from the hydrolysis of 

 proteins by strong mineral acids, or the dark 

 products formed by the action of oxydases 

 upon aromatic or heterocylic phenols may 

 sometimes be shown to be related to the 

 melanins, but until that relationship is demon- 



