Some very important experiments have recently 

 been made by M. de Quatrefages on the vitality of 

 the spermatozoa, or essential part of the seminal 

 secretion in fish.* From these experiments he 

 concludes that for each species of fish there is a 

 fixed temperature which is most likely to insure 

 successful fecundation. The facts which he thus 

 arrives at are generalised in the following table : 

 For fish which spawn in winter, as 



the salmon and trout, the proper 



temperature is from ...... 43 to 46 Fahr. 



For fish which spawn in early spring, 



as the pike ......... ^ ... 46 to 50 



For fish which spawn in late spring, 



as the perch ......... 57 to 61 



For fish which spawn in summer, as 



the barbel ............ 68 to 77 



These temperatures should consequently be those 

 of the water employed in the artificial fecundation 



The practice of artificial breeding may be divided 

 into five distinct phases namely, (1) Exclusion, or 

 the removal from the parent fish, of the male and 

 female generative elements ; (2) Fecundation, or 

 the application of the product of the male to that 

 of the female; (3) Foetation, or the process of 

 development of the embryo in the egg ; (4) Extri- 

 cation, or the escape of the embryo from the ovum ; 

 and (5) Feeding. We shall now mainly follow the 

 directions given by M. Coste,* whose experience in 

 this department of industrial science must give 

 peculiar value to his suggestions. 



EXCLUSION AND FECUNDATION. 

 The fish upon which we wish to operate should 

 be taken, if possible, immediately off the spawning 

 ground at the period when they are just about to 

 deposit their spawn. The following table shows 

 the principal periods of spawning, in these countries, 

 of the more important British fresh-water fish. It 

 must be borne in mind, however, that it is, in many 

 cases, impossible to fix with certainty the exact 

 periods, as these vary .considerably with locality 

 and temperature : 



Name of Fish. 



Salmon (Salmo solar) 



Salmon-trout (Salmo trutta) 

 Common trout (Salmo fario) 

 Great Lake" trout (Salmo ferox) 

 Northern charr (Salmo umbla) 

 Smelt (Osmerus epcrlanus) . . . 

 Grayling (Thy mallus vulgaris) 



Pike (Esox lucius) 



Carp (Cyprinus carpio) 

 Barbel (Barbus vulgaris) ... 

 Tench (Tinea vulgaris) 

 Carp-bream (Abramis brama) 

 Chub (Leuciscus cephalus) ... 

 Perch (Perca fluviatilis) 



Period of Spawning. 

 From Nov. to Feb. 

 From Oct. to Jan. 

 From Oct. to Jan. 

 September. 

 Nov. and Dec. 

 March and April. 

 April and May. 

 March and April. 

 May and Jun. 

 May and June. 

 June. 

 May. 



April and May. 

 April and May. 



' .". 



