PRACTICAL FISH-CULTURE. 575 



species of roe "which swell immediately wheu brought into contact with 

 water, thus in-eventing the entering of the spermatozaa, and under all 

 circumstances.it is a method which can be highly recommended : 



1. When operating on species of roe which does not swell rapidly, 

 and when loss of time between pouring in the milt and the roe, endan- 

 gers success. With the roe of the Coregonus this loss of time is but very 

 brief; with that of the species of Salmo and Tnitta, in employing the 

 '•moist" method, about five minutes. 



2. When you have only one fish containing milt for several containing 

 roe, or whenever the quantity of milt is small. 



3. Whenever roe is to be impregnated whose nature, when brought 

 into contact with water, is not well known. 



Every pisciculturist has, no doubt, often made the experiences men- 

 tioned under Nos. 1 and 2. The case mentioned under No. 3 came under 

 my personal notice on the 25th of November, 18G9, while artificially im- 

 pregnating the roe of the Coregonus manvna. The nature of this roe 

 was, at the time, new to me. As a precaution, I employed the ^'dry" 

 method, which under all circumstances is more certain of success, in the 

 presence of the royal superintendent of fisheries, Mr. Jeserich, and other 

 gentlemen. Every one of the eggs 0])erated upon was developed suc- 

 cessfully.* In the year 1872, during the month of November, I repeat- 

 edly succeeded, by the " dry" method, in impregnating the roe of Core- 

 gonus Wartmaymii in Lake Puis, in the district of Soldin, province of 

 Brandenburg, because of the circumstances mentioned under Nos. 1 and 

 2. The eggs impregnated in this manner developed regularly and very 

 successfully. 



After all my experiences in employing the " dry" method, I can vouch 

 for its successful results, provided the above-mentioned precautions are 

 taken. 



If this method is not successful, the failure must be ascribed, not to 

 the method itself, but to other circumstances. 



Tankow, Aiwil G, 1874. 



ALEXANDER STENZEL, 



Inspector of Fisheries. 



c— fish-cultuee in salt oe brackish water. 



By Theodore Lyman, Fisli- Commissioner of Massachusetts. 

 When shores are not bold, and have extensive shallows, there is often 

 a considerable zone of sea which produces few valuable fishes, although 

 swarming with fry and with small Crustacea and mollusca. In Norway 



* As the piscicultural establishment at Tankow' was uot comuienced till the middle 

 of November, 1869, there was a lack of suitable water for receiving the roe of Corego- 

 nus marwna. In the beginning, it developed regularly, but was soon spoiled by the 

 impurities of the water and its low temperature. Some eggs placed in purer water, 

 with a higher temperature, developed fish which reached the age of three weeks. Dur- 

 ing this spring, (1874,) the Coregonus marwna has been raised successfully. 



