452 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



The female carries the eggs until June or July of the follow- 

 ing year, at which time they hatch out. The young crab 

 remains about eight days longer attached to the parent, after 

 \vhich it separates and takes care of itself. The animals are 

 generally collected in July, August, and September, the cap- 

 ture being effected by means of small lines to which pieces of 

 fish, frogs, etc., are fastened. The best time for this purpose 



is during warm moonlight nights. 10 C^ March 1,1873,41. 







CULTURE OF THE STEELET. 



Dr. Knoch, in a communication upon the artificial culture 

 of the sterlet (a much esteemed small species of sturgeon 

 found in the River Volga), remarks that the best food for the 

 newly hatched fish consists of the various species of Cyclops 

 and Daphnia^ such as are developed in quantity in connec- 

 tion with aquatic plants, like the w^ater - cress, etc. These 

 are devoured by this fish as greedily as they are by the 

 whitefish {Coregonus) and the oihav Salmoyiidcey^Nhich attain 

 a wonderful growth in the course of four months. 



Dr. Knoch refers to specimens of both the eggs and of the 

 young fish prepared by him, in bichromate of potash, as ex- 

 hibiting a remarkable state of preservation, and as being in 

 a condition suitable for investioatinoj the various stao-es of 

 growth. In the same connection he also remarks that the 

 method of dry impregnation which has been so successful 

 with the salmon and trout is not suited to the sterlet, since 

 the eggs, like those of many other fish (the CypTinidce\, or 

 Carp, .especially), are so glutinous as to stick immediately to 

 any object that they may touch, so that, when gathered from 

 the parent and stirred together, they adhere to a degree 

 which prevents the proper penetration by the spermatozoa. 

 Bull. Soc. Imp. des JVaiiiraUstes de Moscow, 1872, ii., 351. 



TREATMENT OF FISH-PONDS. 



Where carp or other fish are kept in ponds or restricted 

 localities, the fish, after spending the Avinter in a lethargic 

 sleep, or at least rest, at the bottom, are frequently observed 

 to rise to the top and swim violently on the surface ; and un- 

 less the entire body of water of the pond be changed, or the 

 fish transferred to some other locality, they inevitably die, 

 this fate sometimes involving the entire population. The 



