228 SALMONID^ OF BRITAIN. 



jousliing up places where the entrance is more or less impeded, and thus causing 

 them to employ their snouts for this purpose. 



At the Howietoun fish-farm, one fact used to be very patent, that the form of 

 trout least alarmed at the presence of strangers was the Lochleven, which had 

 been hatched and reared there, coming immediately to the surface for food, making 

 the water bubble with their numerous forms, while they allowed themselves to 

 be removed by means of a hand-net ; the American char kept more to the mid- 

 water ; while the common brook trout, which had been obtained when young from 

 the burns, were so cunning that the very sight of a net caused them to dive down 

 and remain at the bottom. Some of the young raised at Howietoun are observed 

 to take on cannibal propensities, when if small their colour becomes yellow, their 

 teeth abnormally developed, while they rapidly augment in size. At Loch Leven 

 during the breeding season these fishes are observed to push up rivers to deposit 

 their spawn, and in these localities the young are hatched and the par reared. In 

 fact their habits appear to be migratory to a qualified extent, the par not leaving the 

 burns for the loch until they are from ten to eighteen months of age. 



This form of trout agrees, in many respects, with the variety of the sea trout 

 termed Whitling, Salmo albus (see p. 159 ante), for in the young state it usually 

 has the same short head, preopercle with a very indistinct lower limb, and a num- 

 ber of caBcal appendages. Unless the examples from Howietoun which I have 

 dissected are exceptions, it would seem that change of locality to a smaller piece 

 of water has been coincident with a decrease in the number of the jiyloric 

 ajipendages, coupled with a decided lengthening of the head. 



breeding. — Similar to the brook trout elsewhere, these fish at Loch Leven 

 ascend the streams for the purpose of spawning towards the end of September or 

 commencement of October. The size of the eggs of these fishes has already been 

 referred to (pp. 25, 208), but it would seem that there may be slight yearly varia- 

 tions ; thus in 1885 they were slightly smaller at Howietoun than in 1884, for in 

 February, 1885, I found the average size of the eggs from seven-year-old parents 

 was 0'24 in., but some were 0"20 in., others 0-22 in. in diameter. In some seasons, 

 however, among those spawned the second week in December, a considerable per- 

 centage were observed larger than the eggs obtained earlier in the season, thus 

 the average size from old fish was 21 in., the largest was 27, and the smallest 

 0'175. This leads one to believe that both the age of the fish and the period of 

 the season have to be taken into account when considering the size of the eggs. 

 Probably one reason why young fish do not give such large eggs as older parents 

 is, that in the first the nutrition, which is consumed, goes both to assist in the growth 

 of the parent fish and the formation of the ova, whereas in old fish their growth 

 has not to be taken so much into account. The disastrous results of employing 

 the eggs or milt from young parents, has been already referred to* (seep. 26 ante). 

 At Howietoun the milt of the males appears to be ripe at least three weeks prior 

 to the eggs of the females, and although among the young, males are the pre- 

 dominant sex, at five years old they are commencing to be scarce, and become 

 very rare at six. 



September 3rd, 1884, a Lochleven trout hatched in 1878, in pond twelve, was 

 accidentally killed, and it weighed with its ova 2 lb., the eggs comprising \ lb. 

 of that weight. These eggs were carefully counted by Mr. Thompson, and found 

 to be 1944 in number, or 129G to each pound's net weight of fish after removing the 

 eggs, or 972 to each pound's gross weight of fish, or before the removal of the eggs. 



In October, 1866, in one which died of fungus, I found three eggs from the 

 previous year adherent to the pyloric cteca. In one fine female the right ovisac was 

 full of healthy looking eggs, while the left had merely its upper two-thirds full, 

 and from its lower portion depended a whitish membrane, containing some eggs 

 from the preceding season. 



These fish about the breeding time spring out of the ponds, and rush over their 



* In 1881 Sir James Maitland fertilized the ova of the Lochleven trout witli the milt of the 

 sea trout, and 95 per cent, hatched (sec Professor Easch's Experiments, note, p. 48 ante). The 

 colour of the eggs has been referred to at p. 208. 



