498 EEPOKT OF COMMISSIONER OF FISH AND FISHERIES. 

 4. — THE FECUNDATION OF SPAWN. 



Those fish which spawn on the sand, for instance, the tront, the lava- 

 ret, and the whole family of salmon, prodnce eggs which are easily 

 separated, and which do not stick to other objects ; but those species 

 which deposit their spawn on aquatic plants — the carp, the pike, the 

 l^erch, &c. — produce glutinous eggs, which adhere closely to the plants. 

 The artificial fecundation of spawn of the first kind is also done in two 

 ways : by the " moist" and by the " dry process." The " moist process," 

 which is the more ancient, is followed in most foreign establishments of 

 I)isciculture ; the "dry process," invented by the Eussian piscicultur- 

 ist, Y. P. Yrasski, has been adopted in nearly all the Eussian estab- 

 lishments, and has even been introduced into some foreign ones. The 

 difference between the two methods is apparently very insignificant, 

 but the results obtained by the " dry process" are by far the more 

 advantageous. The "moist process" consists in taking a vessel of sand- 

 stone, of porcelain, or of wood, which must be perfectly clean, and con- 

 structed in such a manner as to have an opening equal in size to the 

 bottom, or a little larger. The bottom must present an even surface, 

 so that the eggs can be freely spread on it. 



Enough water is i)oured into the vessel to cover the bottom to the height 

 of two or three inches. The temperature of the water depends on the 

 species of fish. The most convenient temperature for trout and salmon 

 is from 39° F. to 50° F. The same temperature is good for those species 

 which spawn in winter. For the pike it must be 41° F. to 50° F. ; for 

 the perch and the whole family of sturgeons, from 57° F. to 61° F. 5 and 

 for those fish which spawn in summer from 68° F. to 77° F. In one 

 word, it is necessary that the temperature of the water used for arti- 

 ficial fecundation is as near as possible like the average temperature 

 in which the species lives that is to be operated upon. A difference 

 of 6° to 8°, more or less, may stop the fecundation completely. 



After this, one takes a female fish with the left hand and holds it per- 

 pendicularly above the vessel, The eggs generally fall into the vessel 

 by their own weight, but if this is not the case one presses the belly of 

 the fish gently with the forefinger of the right hand from top to bot- 

 tom. After having gathered the spawn of the female in the vessel the 

 milt is extracted from the body of the male fish in the same manner. 

 When the water assumes a turbid and milky appearance, the spawn is 

 mixed with the milt by means of a feather or the tail of the male fish. 

 After 5 or 10 minutes the fecundation has operated ; then the spawn 

 is washed, the water in the vessel renewed several times, and the eggs 

 placed in basins destined for their reception. 



In order to fecundate spawn a peculiar apparatus is also used, con- 

 sisting of a sieve with a metal tissue narrow enough not to let the eggs 

 pass through, nor to allow them to be entangled in the meshes. The 

 sieve is plunged into a vessel filled with water 5 its sides can be either 



