Vol. XX 

 1903 



Recent Literature. 22V 



Mr. Jacobs's brochure contains three half-tone plates, illustrating the 

 houses with their colonies of breeding birds, and the general narrative of 

 the founding and increase of the colony is followed by sections entitled: 

 * Return from the South,' giving the dates of spring arrivals from 1891 

 to 1902 ; ' Nest Building, Deposition and Number of Eggs, and Incuba- 

 tion,' and relates the manner of nest building, the number of eggs to the 

 set, and the length of the period of incubation. The record shows that 

 a total of 1 150 eggs were laid during the seven years, and that 850 young 

 reached maturity. 'The Growing Young and the Parents' Care' is the 

 title of a most interesting and instructive chapter, and is followed by: 

 'Something about Their Food'; 'Their Enemies, Causes of Death, 

 etc' ; ' Off to the South ' ; 'A Chapter on a Cabinet Series of Their 

 Eggs'; and 'On the Construction of Houses.' The author says: "I 

 have robbed my pets but I do not wear their feathers in my hat ! " Dur- 

 ing the seven years of his fostering care he confesses to having taken 

 eleven sets of eggs for study, of which one had been deserted, and the 

 others were soon followed by the deposition of second sets. The sets 

 vary in number from 3 to 7 eggs to the set, and the size of the eggs is 

 largest in the smallest set, but the smallest average size does not alwaj's 

 coincide with the largest number of eggs to the set. 



In short, Mr. Jacobs's history of his Martin colony is a valuable contri- 

 bution to ornithology, as regards both the economic and natural history 

 phases of the subject. — J. A. A. 



Pycraft on ' The Significance of the Condition of Young Birds at 



Birth.' ^ — Mr. Pycraft believes that too much stress has been laid by 

 svstematists on the widely diverse conditions the young of different 

 groups of birds present at birth, as regards their helplessness or other- 

 wise, and whether clothed or more or less naked ; and further claims that 

 the significance of these conditions has been misunderstood. "The real 

 explanation of the matter," he says, "seems rather to turn upon a ques- 

 tion of expediency, designed, so to speak, to reduce infant mortality." He 

 claims to present facts "strong enough, on the one hand, to refute the 

 older views, and on the other, to justify the theory, firstly, that birds were 

 originally arboreal and their young nidifugous ; secondly, that nidicolous 

 habits and helplessness of young birds are specialized adaptations to an 

 arboreal or gregarious mode of life ; and, thirdly, that the young of galli- 

 naceous birds form a link in the chain of evolution of nidifugous habits. 

 The free finger tip and arrested development of the outer quill-feathers 

 point to a prior arboreal habit, whilst the accelerated development of the 

 inner quill-feathers indicates an adaptation to enable the young to escape 



'The Significance of the Conditiort of the Young at Birth.. By 'W. P. 

 Pycraft, A. L. S., F. Z. S. Popular Science Monthly, Vol. LXH, Dec. 1902, 

 pp. I 08-1 16. 



