i69 PHILOSOPHICAL TRANSACTIONS. [aNN0 177I. 



About the spawning season, great care must be taken, to keep out all aquatic 

 fowl, wild and tame, from the ponds; for geese and ducks not only swallow the 

 spawn, but destroy still more of it, by searching the weeds and aquatic plants. 

 It is therefore a general rule, to send twice a day, a man round the ponds, to 

 scare all wild fowl, viz. swans, geese, ducks, cranes, and herons. 



Sometimes crusians and carp, or tench and carp, being put together in a pond, 

 and the males and females of each kind not being in a just proportion to one 

 another, the different species mix their roe and milt, and thus produce mules or 

 mongrel breeds. The mules, between carjj and crusians, seldom and slowly at- 

 tain the size which carp are capable of; tiiey are very deep, and shorter in pro- 

 portion than carp, but of a very hardy nature. The mules between carp and 

 tench, partake of the nature of both fish, come to a good size; but some part of 

 their body is covered with the small slimy scales of a tench, and some other part 

 has the larger scales of carp; their flesh approaches nearer to that of a tench, 

 and they are likewise of a less tender nature than the common carp : this latter 

 kind of mule is called in Germany spiegel karpe, i. e. the mirror-carp, the blotches 

 with large scales among the smaller ones bfing considered as mirrors. Whether 

 these mules are capable of propagating thfir species, he cannot affirm ; never 

 having made any experiments on that subject; nor has he heard any thing said 

 on that head with any degree of precision, or founded on experience. In some 

 ponds in Lancashire, he was told, by a gentleman of great worth and honour, 

 both these kinds of mules are now and then found. He thinks it however not 

 advisable to put carp and tench, or carp and crusians, in one pond, unless it 

 be done for experiment's sake; in which latter case, a small pond, free from 

 other fish, with one or two fish of each kind, will be sufficient to gratify curi- 

 osity, without debasing a generation of carp in a large pond. 



The young fry being hatched from the spawn, by the benign influence of the 

 sun, they are left the whole summer, and even the next winter, in the spawning 

 pond; in case the pond be so deep, that the suffocation of the young tender fry 

 under the ice, in a severe winter, is not to be apprehended, for it is by no means 

 advantageous to take them out in the first months of their existence. However, 

 if the shallowness of the pond, its cold situation and climate, make it necessary 

 to secure the fry against the rigours of the ensuing winter, the water of the pond 

 must be let off; the fry and old fish will gradually retire to the canal and ditches, 

 which communicate with the hole in the middle of the pond, and a net, with 

 small meshes, is then employed to catch both the fry and old ones. The old 

 breeders are then separated from the fry, and both kinds put in separate ponds, 

 that are warmer and more convenient for the wintering of these delicate fish. 

 Care must be taken to fix on a calm, mild day, at the latter end of September, 

 for catching the fry out of the spawning-pond. 



