EGGS AND ALEYINS 77 



I do not say that these " differences " will be found of constant 

 occurrence, but they arc worth noticing. At Luss 1 have had the 

 advantage of studying the ova of fish from commercial hatcheries as 

 well as of fish native to the district, and upon the eggs and the resultant 

 alevins and fry I have made notes at various times. 



I think that the facts noted regarding the earliest stages in their 

 respective careers point to a marked distinction between S. salar and 

 S. trutta, and to a considerable variation between the various breeds of 

 trout irrespective of whether they happen to be migratory or non- 

 migratory. 



Distinctions between the fish at later stages of growth will be pointed 

 out as these stages are being considered. 



A considerable number of " monsters," or deformed alevins, is 

 always discovered amongst sea-trout hatched under artificial conditions, 

 although oddly enough few are ever found in the salmon boxes. No 

 very accurate estimates have been made by which it can be deduced 

 that the number of monsters is variable or fairly constant. In all 

 probability much the same number appears amongst naturally hatched 

 fish, but under natural conditions few deformities have any great chance 

 of being seen, and doubtless few survive to be seen. Some interesting 

 notes on this point are given in a work on " The Teratology of Fishes " 

 by my friend Dr. James F. Gemmill, Lecturer on Embryology at 

 Glasgow University. He states that the following figures have been 

 found to apply to deformities amongst the Salmonidce : — i in 50, and 

 I in 280 (Rauber); i in 600, none in 600, and 68 in goo (Schmitt); i in 

 200, and I in 350 (Gemmill); over 100 in 400,000 (Coste). He adds 

 this interesting statement : — " It is worthy of note that the frequency 

 with which double monstrosity appears in the eggs of fishes is not far 

 from corresponding with its frequency in those of the fowl." 



Sometimes sea-trout with truncated snouts, spinal curvature, or 

 stunted tails are caught, the largest " deformity " I have seen being 



