INTERESTING PHENOMENA. 55 



Such trials as I made to keep some longer 

 were unsuccessful, whether owing to not giving 

 them proper food, or not affording them a 

 sufficient supply of fresh and cold water. 

 Eemember they are not, in this early stage, so 

 helpless as at first might be imagined : they are 

 quick in their movements ; this and their 

 minuteness of size, and their tendency to nestle 

 under stones, tolerably secure them. Let me 

 advise you, whenever you have an opportunity, 

 to engage in the breeding of any of the 

 SalmonidsB of which you can procure the ova 

 and the milt, whether of the trout, salmon, or 

 charr (the facilities in each instance are much 

 the same), not to lose it. You will find the 

 subject interesting, especially if you call in aid 

 the microscope; then, you may witness the 

 progressive formation of a living being in all 

 its complicated organisation, from its crude 

 elements comprised in the substance of the 

 egg, to compare delicate things with coarse 

 nature's work with man's like the building 

 up of a house, or the construction of a ship ; 

 you may watch the changes, the metamor- 

 phoses in their course ; you may see demon- 

 strated in the transparent structure of the 

 E 4 



