98 Recent Literature. [jan^ 



Riddle's 'A Study of Fundamental Bars in Feathers.'' — This is a study 

 of abnormalities in feathers and their cause. Defects in the development 

 of feathers are not uncommon, and are not confined to particular species, 

 nor to any particular condition of existence, as to birds in a state of domes- 

 ticity, but apparently occur in all birds. A feather does not present a per- 

 fect, uniform continuity from tip to tip, but is made up of an apposed 

 series of faint 'fundamental bars,' and the defects are found to appear at 

 these points of apposition. It is assumed that each segment or ' funda- 

 mental bar' represents a day's growth, and also the amount of feather 

 growth between two low blood-pressures. The period of lowest daily 

 blood pressure has been determined as occurring between 1 and 6 a. m. 

 "Since," says the author, "these defective lines are laid down at approxi- 

 mately the same time each day — as is proved by the regularity in the 

 distances separating them — we are forced to the conclusion that the 

 defective lines are normally laid down at night, and that a lowering blood- 

 pressure is associated with the production of defective areas, and, there- 

 fore, of defective lines, for, that the defective line stands for the initial 

 stage of the defective area is as certain as that a defective area has more 

 dimensions than a line." These conclusions are based on experimental 

 and histological research, and appear to have an important economic 

 bearing. The value of the ostrich plume output for South Africa alone 

 is annually depreciated, it is said, to the extent of £250,000 by defective 

 development, which Mr. Riddle traces to malnutrition due to defective 

 diet and other hfe conditions that it may be possible to remedy. Such 

 researches should also give the final quietus to the belief in ' re-pigmenta- 

 tion' and ' rejuvenation ' of old, full-grown feathers, which seems to have 

 still a persistent hold upon the minds of certain ornithologists abroad — 

 a relict of fonner days when feather growth was little understood, and 

 casual observation of external appearances were awarded undue value. — 

 J. A. A. 



Hopkins on the Bony Semicircular Canals of Birds.- — The purpose of 

 this in\'estigation was to determine "whether there is any relation of the 

 comparative dimensions of the bony semicircular canals of the ear of birds, 

 either to mode of locomotion, or to genetic affinities." These canals were 

 examined in about 75 species of birds, representing all orders, and all 

 modes of locomotion — running, swimming, diving, flying, and all degrees 

 and modes of flight. The measurements are tabulated. The results show 

 (1) that birds of the most diverse forms of locomotion and very diverse 

 aflanities have the same relative sizes of semicircular canals; (2) that 



1 A Study of Fundamental Bars in Feathers. By Oscar Riddle. Biological Bulle- 

 tin, Vol. XII, No. 3, February, 1907, pp. 165-174. 



2 On the relative dimensions of the Osseus Semicircular Canals in Birds. By 

 May Agnes Hopkins. Biological Bulletin, Vol. XI, No. 5, October, 1906, pp. 253- 

 264. 



