ABSTRACTS. 293 



chemical constitution of the blood as measured by the refractive 

 index. Some figures on the point follow : 



Source of Blood. nD 



Fowl (Gallus sp.) 1-34537 



(Mean of data from 10 birds of different hereditary constitutions) 



Guinea (Numida meleagris) 1.34184 



(Mean from 6 birds) 

 Hybrid (Gallus S X Numida ?) • 1-34179 



FITTING LOGARITHMIC CURVES BY THE METHOD 

 OF MOMENTS.* 



The use of logarithmic curves in the analysis of various kinds 

 of biological and agricultural data is rapidly becoming wide- 

 spread and general. It was first shown by Lewenz and Pearson 

 that the growth of children followed a logarithmic curve. Pearl 

 demonstrated that the phenomena of growth and differentiation 

 in Ceratophyllum also followed a logarithmic curve. Donald- 

 son and Hatai in a series of papers dealing with the growth and 

 quantitative relations of the whole organism and its various 

 parts in the white rat and the frog have shown that the same 

 law holds for growth in those forms. 



Other biological phenomena than growth follow a logarithmic 

 law. Pearl, in a case of regulation of the shape of abnormal 

 €ggs, and later Curtis for normal eggs, have shown that the 

 changes in size and shape of successively laid eggs are graduated' 

 with a logarithmic curve. Work now in progress in the Biologi- 

 cal Laboratory, Maine Experiment Station, of which only a 

 preliminary notice has yet been published, shows that generally 

 the change in milk flow with age in dairy cattle is logarithmic. 

 Several years ago Holtsmark pointed out that the relation be- 

 tween the number of food units required and the milk yields 

 of different animals was logarithmic. 



From this incomplete review of the literature recording the 

 use of logarithmic curves in biological and agricultural investi- 

 gations it is clear that the workers in these fields will, as time 



*This is an abstract of a paper by John Rice Miner, having the same 

 title and published in the Journal of Agricultural Research, Vol. Ill, pp. 

 411-423. 1915. 



