766 EXPERIMENT STATION RECORD. 



on the metJibolisiii nf .in .iiiiinal is regular and <-(;ii.staiil and can ha exi)ressed 

 in a definite furve. 



A micro-respiration apparatus correction, A. Kkogii ( Bioclieni. Ztschr., 66 

 {191.'/), No. 6, p. 512). — Fornuilas and values jjiven in a previous article (E. S. 

 R., 32, p. 67) are corrected. 



ANIMAL PRODUCTION. 



Pattern development in mammals and birds, G. M. Allfn {Amcr. Xat., 

 4H (1914), Nos. 511. pp. SH5-412; 512, pp. J,Gt-m; 57.3, pp. 550-566. figs. 62).— 

 The author summarizes the principal ix)iuts of this paper as follows: 



" In mammals and birds that normally are completely pigmented there are 

 certain definite iwints of the body from which as centers the tendency to de- 

 velop pifrnient in the epidermal struotui'es may become less and less. Outward 

 from each of these centers pijinient formation spreads to include very definite 

 areas which in wholly pigmented animals overlaj) slightly at their borders or 

 are at least contiguous. 



"A reduction in the area covered by any of the^e primary' patches results in 

 a white mark at the line of junction of two contiguous color patches, where no 

 pigment is produced. These white marks between the primary patches are 

 spoken of as primary breaks. 



" Through a study of the breaks in jiied individuals of domesticated species 

 of mammals and birds the boundaries of the primary patches have been deter- 

 mined. These are homologous in the two groups and subject to a certain 

 amount of variation in different types. They are: A median crown patch, un- 

 paired, and five paired patches on the opposite sides of the body, which are 

 named from the general areas they cover, the ear, neck, shoulder, side, and 

 rump patches. Their limits are more precisely defined under the different 

 species treated. 



" These patches are physiologically independent of each other and may be 

 differently colored in the same individual. 



" Pied patterns among many wild species have been brought about through 

 the areal reduction of these pigment patches in a definite way. so that the 

 white markings resulting as breaks between the reduced patches have become 

 fixed and form a permanent part of the normal pattern. 



" In several wild species this development of white markings is shown to be 

 even now taking place, but the amount of pigment reduction is still fluctuating 

 so that the white markings vary much in extent with different individuals. 



" Tlie development of such white markings takes place probably by little and 

 little, so that the departure from type is not so great as to arouse antagonism 

 against the varying individual on the part of others of its species. Also, the 

 gradualness of the change allows the species to become accommodated to any 

 disadvantage that miifht concomitantly arise. 



"The converse of this centripetal style of pigmentation is present in many 

 species, and results in pigmentation (commonly black) at the extremities or 

 along lines where primary breaks occur in the centripetal fot-m, namely, at the 

 tip of the nose, ears, tip of the tail, or the toes: possibly the black dorsal stripe 

 is due also to centrifugal pigmentation. Patterns may develop, as in certain 

 antelopes, by a white break between patches of the two types." 



Fitting logarithmic curves by the method of moments, J. R. Miner (U. S. 

 Dcpt. .if/r.. Jour. Agr. Research, S (1915). No. 5, pp. Jfll--'i2.3). — In this paper. 

 which includes an introductory statement by R. Pearl on the u.se of logarithmic 

 curves in biological and agricultural investigations, the author attempts to im- 



