RURAL ECONOMICS. 393 



Notes on the parasitism of Cytodites nudus and Haemaphysalis chordeilis, 

 P. B. Hadley (Science, n. ser., 30 {1909), No. 77'/, pp. 605, 606.).— The author 

 describes the conditions of infection as observed in 2 cases of acariasis. caused 

 by Cytodites nudus, occurring in the yards of the Rhode Ishiud Station. In 

 the first case, that of a female golden pheasant, mites were found to have per- 

 forated both the pericardium and the wall of the gall bladder. The second 

 case of infection was that of a fowl received from a poultry yard near the 

 station. 



A tick {Hccmapliysalls chordeilis) is repoi'ted to have occurred on young 

 turkeys at Norwich, Vt., June, 1909, in such numbers as to kill 40 of a flock of 

 46. The ticks were first observed in the latter part of May when the turkeys 

 were about a week old. The parasite was found largely in the region of the 

 neck, most of the birds that were infested carrying from 70 to 80 full-grown 

 ticks as well as many more immature forms. 



Naphtha soap as a disinfectant, S. K. Dzerzgowski and V. L. Stepanova 

 (Arch. Set. Biol. [St. Petersb.], 14 {1909), No. J,, pp. 283-303).— A contribution 

 from the Imperial Institute of Experimental Medicine at Cronstadt, in which 

 the chemical and physical i)roperties of naphtha soap are considered. 



Meat inspection in Hungary, A. Laszlo {Vet. Jour.. 6o {1909), No. J/IS, pp. 

 '5o3~oo8). — An account of the methods followed in the inspection of meat in 

 Hungary. 



RURAL ECONOMICS. 



Concerning' the actual significance of the law of diminishing returns in 

 agriculture, O. Auhagen {Landir. .Jalirb., 38 {1909), Ergduzuiigsb. 5, pp. ^91- 

 530). — This paper critically examines the law of diminishing returns and main- 

 tains that it has no scientific value from the standpoint of agriculture. 



According to the author, the development of agricultural technique has re- 

 sulted in increased production of the means of subsistence to such an extent 

 that not only is the totality of production greater, but the proportionate share 

 falling to the individual is greater notwithstanding the enormous increase 

 in population since the law was formulated. At the same time a limit is 

 reached in agricultural practice when a further expenditure of capital and 

 labor will be fruitless. The author points out these limits as regards the oper- 

 ation of natui-al forces as well as those under which plants grow to yield the 

 best I'eturns. The depth of plowing, the amount of plant food and moisture 

 in soils, temperature, sunshine, the minimum of room for plant growth, the 

 time necessary for plant development, and many other factors determine the 

 maximuru yield. 



The stimulus to agricultural production was in a certain sense the increase 

 of population itself. This necessarily forced mankind to further progress 

 which resulted in the development of the technique of agriculture. " It is 

 an error to deduce as a law from the increase of population and the corre- 

 sponding increase of the means of subsistence the relative decrease of land 

 productivity and to set down technical progress only as an incidental or even 

 as an exceptional check or breach of the law. Progress in land productivity 

 yields itself also as an economic law resulting from the increase of popu- 

 lation." 



At the same time the author recognizes a limit to man's ability to make 

 the earth yield her increase of products, chiefly because in agriculture even 

 the scientiflc farmer is dependent to a considerable extent upon the forces 

 of nature, and so maintains that man will be able to reach his highest stage 

 of development only as he learns to control completely the forces of nature. 



