CULTURE OF THE WHITE-FISH. 533 



\\ -ere slightly opalescent only, and when allowed to thaw they contracted as before, ultimately 

 going ou to cleave in an irregular manner, the ruptures in their sacs having healed. Slighter 

 reductions of temperatures to -IIP F. and 48 F. retarded without destroying the contractions. In 

 such cases the commencement of cleavage was delayed. I'.y raising the temperature moderately 

 the movements were accelerated ; but at about 80 F. (it is dillieult to speak with certainty of the 

 temperature actually obtained by the object) the contractions were, arrested, the yelk-ball 

 becoming globular, and the oil-globules being scattered. Such eggs, however, soon recovered 

 themselves when left at 58 F., and cleft in even less time than eggs did which had not been 

 warmed. In other eggs, heated in a chamber at lOli F., the cleavage was retarded to three times 

 the usual period, and when it took place was wanting in symmetry. The yelk began to become 

 opalescent at about 103 F. ; but a true coagulation of the albumen did 'not take place, the yelk 

 being fluid and opaque. Thus a temperature too low or too much elevated retards or arrests 

 the contractions, but they are not destroyed before commencing physical and chemical changes 

 set in.' 



"Whether the point at which the contractions of the yelk ceased was the point at which 

 vitality left the egg, might or might not have been the fact, but it is quite evident that the egg 

 was, at the temperatures stated, in an abnormal state, and the necessity of sustaining a tempera- 

 ture around the eggs of fishes between these extremes is apparent, if they are to be kept in their 



i 



most favorable condition. 



"Mr. Green and Mr. Wil mot both procured -eggs this season from the Detroit River. Mr. 

 Green made use of a newly devised apparatus for hatching, that proved to be a most excellent 

 contrivance, lioth for the economy of space and the facility for caring for the eggs. By this 

 method he will be enabled to hatch five or six times the quantity of eggs in the same building. 

 The young fishes were distributed in accordance with the excellent plan adopted by the New York 

 commissioners for supplying demands from all parts of the State, without expense, on application. 



" The success attained by these persevering experiments is now complete, and the White-fish 

 may be restored by artificial propagation, to the same extent as the Salmon, or the Brook-Trout, or 

 the shad. As has been shown, the White-fish has advantages in this particular that the other 

 species have not. The obstruction of streams is no obstacle in the way of their multiplication, 

 because they have no necessity of ascending them, and, unlike the Trout and the Salmon, they 

 cannot be suspected of eating each other. 



"Attempts at feeding the young fishes have all been failures, and the only natural food that 

 has been found in their intestines is the species of Diatomacece reported by Mr. Briggs. But as 

 they are more vigorous and strong in the earlier stages of growth, there is not the same necessity 

 of caring for them until they are partly grown, and they should be put into the waters they are 

 to inhabit soon after the ovisac is absorbed, and allowed to find their natural food for themselves, 

 just as the young shad are treated when hatched artificially. 



"Artificial propagation atlbrds advantages that compensate for all the overfishing and losses 

 that the fish faiuiie sutler from man and natural causes. The great numbers of eggs found in the 

 ovaries of fishes in reality afford little evidence of their capacity for populating the waters. It is 

 a fact, illustrated in nearly if not all branches of the animal kingdom, that the most fecund species 

 do not, by any means, increase the fastest in numbers, but from the greater evils they are subject 

 to, and the greater number of enemies they encounter, there is such a fatality during the earlier 

 stages of growth that the losses balance the numbers produced, and less fecund species, by being 

 better protected, equal them in numbers. The most perfect illustrations of this fact may be found 

 among our lake fishes. The muskellunge, Esox nolilior, has a very large number of eggs. A cast 



