442 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of two and a half years, and was only deterred from continu- 

 ing the business on account of the very low price that they 

 brought at wholesale namely, fifty cents per hundred. He 

 thinks that the physical conditions in the United States are 

 especially favorable to the growth and culture of the medic- 

 inal leech, and that any one entering upon the business 

 could readily command the market here, independently of 

 foreign importations. 



SPAWNING OF THE STERLET. 



According to Professor Owsjannikow, the sterlet spawns 

 in the Volga early in May, on rocky bottoms, the tempera- 

 ture of the water being at 54.5 Fahr. The eggs are readily 

 fecundated by the artificial method. After they have been 

 in the water a few minutes they adhere to any object which 

 they touch. The development of the embryo can be observed 

 in progress at the end of one hour. On the seventh day they 

 hatch. At first the young fish are about one quarter of an 

 inch long. At the age of ten weeks they are nearly two 

 inches long. They feed on larvae of insects, taking them 

 from the bottom. Both in the egg, and when newly hatched, 

 the sterlet has been taken a five days' journey from the Volga 

 to Western Russia, and in 1870 'a lot of eggs was carried to 

 England to stock the river Leith. This species, like many 

 other of the sturgeons, passes its whole life in fresh water. 

 3 A, August 3, 1872, 72. 



TUNNY FISHERIES ON THE SOUTH SHORE OF THE MEDITER- 

 RANEAN. 



Very extensive fisheries of the tunny are carried on on the 

 coast of Tunis, especially that of Sidi Daud, or a small island 

 separated from the main-land by a few yards of water. Upon 

 this island, about a mile in circumference, are the stores, boil- 

 ing and curing houses, oil-tanks, and all the necessary build- 

 ings. The fishing season commences in April and ends about 

 the middle of July, and when in full force is managed by 

 about 200 persons. The entire outfit required for this fishery 

 is valued at $80,000, and the cost of running the establishment 

 amounts to about $30,000 per anrmm, which will give some 

 idea of the extensive scale upon which the work is prosecuted. 



The tunnies, in their spring migration from the ocean to 



