NITROGEN FROM BIRDS 29! 



a manure is greatly increased. The relative value of the nitro- 

 gen in these bodies as compared with the more desirable forms, 

 has been a much disputed question. 



253. Ammoniacal Nitrogen. In ammonia compounds, nitro- 

 gen is used chiefly for fertilizing purposes as sulfate. Large 

 quantities of ammonia are produced in the manufacture of coke 

 and in other industrial operations. The ideal nitrogenous fer- 

 tilizer is a combination of the ammoniacal and nitric nitrogen 

 found in ammonium nitrate. The high cost of this substance 

 excludes its use except for experimental purposes. 



254. Nitrogen in Fish. A large amount of nitrogen is also 

 recovered from the sea in fishes. It is shown by Atwater that 

 the edible part of fishes has an unusually high percentage of 

 protein. 50 In round numbers about 75 per cent, of the water-free 

 edible parts of fish are composed of albuminoids. Some kinds of 

 fish, however, are taken chiefly for their oil and fertilizing value, 

 as the menhaden, but the residue after the oil has been extracted 

 is even richer in nitrogen than mentioned above. Squanto, an 

 American Indian, first taught the early New England settlers 

 the manurial value of fish. 51 



255. Nitrogen from Birds. Immense quantities of waste nitro- 

 gen are further secured, both from sea and land, by the various 

 genera of birds. The well known habit of birds in congregating 

 in rookeries during the night and at certain seasons of the year 

 tends to bring into a common receptacle the nitrogenous matters 

 which they have gathered and which are deposited in their ex- 

 crement and in the decay of their bodies. In former times the 

 magnitude of these rookeries was probably much greater than now, 

 but even at the present time they are of vast extent as shown by 

 Fig. 13, a photograph of wild ducks on Layson Island. The feath- 

 ers of birds are particularly rich in nitrogen, and the nitrogenous 

 content of the flesh of fowls is also high. The decay of remains of 

 birds, especially if it takes place largely excluded from the leach- 

 ing of water, tends to accumulate vast deposits of nitrogenous mat- 

 ter. If the conditions in such deposits be favorable to the processes 



50 Report of the Commissioner of Fish and Fisheries, 1888 : 679. 



51 Goode, American Naturalist, 1880, 14 : 473. 



