ANIMAL PRODUCTION. 677 



" There being such a great variation among ostriches as regards their tend- 

 ency to produce defective feathers, the principle of selection in breeding is 

 strongly enforced." 



" Ostriches, even in good condition, if exposed to inclement weather, may 

 later show constrictions in their growing feathers, which constrictions will re- 

 sult in bars on tlie feathers unfolding. Birds kept under shelter during the 

 same inclement conditions are not likely to produce defective feathers. 



■' The exposure produces a contraction or shrinkage of the skin upon tlie soft 

 growing feather, the latter being thereby constricted in a ring-like manner, 

 which constriction fails to reexpand after the feather leaves the socket. 



" The skin shrinkage does not affect quills, and ripe, or nearly ripe, yfeathers, 

 as the quill is too firm and hard to respond to the pressure. Bars are pro- 

 duced during the soft growing period of the feather. 



"All ostriches are not affected alike by tlie same unfavorable conditions ; 

 some are very responsive, while others are very resistant." 



African ostrich industry, R. B. Mositer (Daily Consular and Trade liptK. 

 [[/. *S'.], 1!)07, No. 2981, pp. /-J).— Statistical and other data are reported re- 

 garding the ostrich industry and the care and management of these l)irds. 



Ostrich, raising in French West Africa, Decorse (Agr. Prat. Pays Chauds, 

 7 (1907), No. 53, pp. 121-133, fig. i).— The possibilities of ostrich raising in 

 French West Africa are discussed and information suiipHed regarding the care 

 and management of these birds. 



Experimental studies in oyster propagation, J. Nelson (New Jersey t^tas. 

 Rpt. 1906, pp. 311-35.^, pis. 13). — A progress report, of the station's investiga- 

 tions on oyster culture and propagation (B. S. 11., IS, p. 73). 



The main reason why artificially produced fry did not develop satisfactorily, 

 in the author's opinion, was the use of water of too low density. " The spat 

 which had set before the water became so fresh seemed to stand . . . [low 

 density] surprisingly well. This is to be explained by the fact that the fry now 

 furnished with shells could shut out the water on the lowest tide when it was 

 least dense, and yet on a flood tide was able to secure sufficient food to make a 

 fair growth. It must also be noted that the water on the bottom, where the 

 oysters are, is somewhat denser than at the surface, where most of our density 

 readings were made. . . . 



" Our experiments with cultch showed that oyster fry prefer to attach to 

 oyster shells, and that the inner or smooth side is more favorable to attachment 

 than the outer side. But even the outer side is superior to most other objects. 

 Oyster fry do not show great choice as between the upper or lower sides, or the 

 liollow or convex sides of cultch. ... 



" We found it advantageous to wash our eggs before fertilization. We had 

 the remarkable result to secure fry with shells developed, only 12 hours after 

 fertilization. This was partly due to the prevailing high temperature — usually 

 it takes 18 to 24 hours, and if the water is cool the shell stage may even be de- 

 layed to the thirty-sixth hour. We have previously called attention to the fact 

 that fry may live and appear lively and normal without shell for days, but such 

 fry will not produce spat. 



" On the other hand, we noticed that immediately after hatching, long before 

 there is a sign of a shell, the fry seek the surface and will cluster on any ob- 

 ject that projects out of the water, just in the surface of the water. Here they 

 will rest and develop as fast as do the free swimming fry, and get shells; the 

 shells will appear as if on the point of becoming cemented to the cultch. We 

 iiave not been able to raise these fry to a later stage. The actual attachment 

 was never completed, but the phenomenon is a noteworthy one. Doubtless, fry 



