Under the most favourable conditions^ four mgms. of nitrogen is 

 fixed per gram of dry matter present in the faeces. 



Nitrogen fixation also takes place in bullock faeces, but to a 

 smaller extent than in horse faeces. Here also it depends on the diet, 

 as it occurs only when animals are fed with cake, and not when they 

 receive grass alone. 



Evidence is adduced to show that fixation is brought about by a 

 mixed culture of Azotohacter and B. lactis aerogenes. Of these the 

 latter is normally present in faeces ; Azotohacter is not, but readily 

 comes in by infection. Both organisms are present in the soil. 



XVII. " Some Experiments on the House Fly in relation to the 



Farm Manure Heap.'" H. Eltringham. Journal of 

 Agricultural Science, 1916. 7, 443-457. 



The possibilities of the manure heap as a breeding ground for 

 flies were investigated. Heaps were made up and left for a certain 

 period to allow of infection ; they were then covered over completely 

 with gauze frames fitted with fly traps, and the flies as they emerged 

 were collected, identified, and counted. 



Manure heaps near to dwelling houses form a prolific breeding 

 ground for the ordinary house fly ; heaps remote from the house, 

 however, are but little frequented, and then only later in the season 

 when the flies have become numerous and widely dispersed. It is 

 shown that the flies do not live in the heap, but only use it as a con- 

 venient breeding place ; they travel backwards and forwards to the 

 house for their food. Care should be taken, therefore, to place the 

 manure heap so far from the kitchen that it is no longer possible for 

 them to continue feeding in the kitchen and breeding in the manure 

 heap. 



Even when this is done, the heap may still remain a prolific source 

 of the biting fly, Stromoxys calcitrans, a blood sucking insect, harmful 

 to man and beast, and of Musca autumnalis. which closely resembles 

 the house fly, but swarms in the open and only enter houses in autumn. 

 Where these are sufficiently numerous they are harmful, and the heap 

 should be treated with an insecticide. 



PLANT NUTRITION PROBLEMS. 



XVIII. " Studies of the Formation and Translocation of Carbo- 



hydrates in Plants. I. — " The Carbohydrates of the 

 Mangold Leaf.'' William Alfred Davis, Arthur 

 John Daish and George Conworth Sawyer. Journal 

 of Agricultural Science, 1916. 7, 255-326. 



Starch is entirely absent from the leaf after the very earliest stages 

 of growth and disappears entirely as soon as the root begins to 

 develop and receive the sugars formed in the leaf. Maltose is entirely 

 absent from the leaf, mid-ribs and stalks at all stages of growth and at 

 all times of night and day. 



During the early stages of growth of the mangold, when leaf 

 formation is the principal function, saccharose is present in the leaf 

 tissues in excess of the hexoses. The reverse holds good later in the 

 season, when sugar is being stored in the root ; hexoses then largely 

 predominate in the leaf. 



In the mid-ribs and stalks the hexoses always predominate and 

 they vary widely in amount during day and night and throughout the 



