56 



Transactions. 



hit on two such striking and extreme examples of different types of growth. 

 The probable weight of the 17 lb. fish each year would be about — 



Fig. 8. 



Conclusions. 



1. The scales of a trout give fairly reliable evidence of age and length 

 attained by the fish each winter. 



2. Some scales are difficult to read, and errors may occur mainly in 

 three ways : (a) The first one or two winter bands are often very indistinctly 

 marked ; (6) in very old fish the winter bands may be so crowded together 

 towards the edge of the scale as to be indistinguishable — possibly in some 

 cases the scale may cease growing altogether ; (c) some scales, whilst clearly 

 marked, are at present difficult to read : when this is the case all scales 

 from the same fish present the same peculiarity. 



3. A true spawning-mark is not uncommon amongst the large males, 

 and is probably formed by absorption of the scale, especially the outer 

 surface, in formation of the tough skin assumed by the males at spawning- 

 time. In other fish the character of the winter band gives in many cases a 

 tolerably reliable indication of spawning. 



4. Under normal conditions trout increase but slowly in length after the 

 third winter. Growth is most rapid in the first two years, and generally 

 the first year shows the best growth of all. 



5. Very rarely does a trout growing in this manner attain a large size 

 (say, over 2 lb.). Large trout almost invariably show a break in the growth- 

 curve when a year of rapid growth succeeds slower growth. After the rapid 



