Mud snail, see Limnaea 32, 34^ 207, 208 



Mud-tube worms (Tubifox, Limnodrilus) , 31, 35 



Uuskrat 192 



Mussels 33, 99, 133, U3 



Uyriophyllum 4.3 



Myxobolus 205, 206» 



Nais 31 



Nannoplankton ,,,... • •• 44 



Nasturtium 43, 152 



Natural feeding in nutrition of pond fishes 10 



Natural gross yield 126 



Natural increase « , 128, 145 



Natural nutrition and food with carps 15 



Natural nutrition, digestion of 16 



Natural nutrition, food quotient 143, 144 



Natural nutrition, of brooks in winter 121 



Natural nutrition of plankton-animals 143 



Natural nutrition, vitamine content 26 



Natural ponds in trout culture 99, 121, 122 



Natural stock 144 



Natural yield of German pond industries 127 



Naturally dammed ponds 191 



Naupliae (larvae of Cyclops species) 32 



Nemura 33 



Neorhynchus 209 



Net, basket 173 



Net plankton , 44 



Net yield 189 



Nets, impregnation of ^ 174 



Neuroptera larvae 33 



New stocking 36 



Nitrifying bacteria ^5 



Nitrogen fertilization ..j 170 



Nitrogen-accumulating bacteria 170 



Nitrogen-binding bacteria /^ 



Nitrogen- free extractive substances 17 



Nitrogen-free pond fertilization 171 



Nodule diseases 205 



Non-parasitic fish diseases 196 



Normal size 6 



Normal weight 9 



North Sea diver 193 



Norway (brown) rat , 192 



Nose disease ., 197 



Nose fishes 15, 16 



Notonecta 34 



Nursery fed trout brood, setting out of 121, 122 



Nursery ponds, early fish-out of 83 



Nursery ponds, late fish-out of 83 



Nutrient animal rests, non-eaten 38 



Nutrient food impoverishment 30 



Nutrient food ratio 18, 19 



Nutrient foods , digestible 18 



Nutrient foods, organic , 18 



Nutrient foods, wealth of 30, /^3 



Nutrient salts 27 



Nutrient substances, digestibility of the 17, 23 



Nutrient substances , primitive 27 



Nutrient-animal evaluation and emergent water plants ,.., 41 



Nutrient-animal production and stock strength , 39, 4,0 



Nutrition, air 13 



247 



