Growth and Development of the Salmonidee. 167 



growth than trout of the same age, and con- 

 tinued to thrive in a way that indicated a 

 robust constitution. This is an instance of 

 the ease with which even dissimilar kinds of 

 salmonoids can be hybridized, and the progeny 

 not being unfertile indicates a near relation- 

 ship between the two species. In these ex- 

 periments, what is called the " dry " system of 

 fertilization of the ova was practised — that is, 

 the ova and the seminal fluid were brought in 

 contact in a pan, without being immersed in 

 water. This system, which was first dis- 

 covered in Eussia, has produced a larger per- 

 centage of fertile eggs than the old method of 

 fertilization in water. 



On the 1st of August of the year 1878 I 

 examined the different small salmonoids in my 

 ponds at Ercildoune. The Californian salmon 

 had been some time previously divided into two 

 lots, and placed in two small ponds, the larger 

 sized fish in one and the smaller in another. 

 Both lots were regularly fed with liver in the 

 same way. I measured the largest and smallest 

 in each lot, and found in one that the largest 

 fish was four inches and three quarters in length, 

 and the smallest three inches and a half. In 



