birds and bilharziasis. 393 



References to Literature. 



Biitschli, O- (1880-89). "Protozoa," Bd. I., Abt. 1-3, in Bronn's 



"Tier-reichs." 

 Cutler, D. W. (1919). "Observations on Soil Protozoa." Journ. 



Af/ric. Sci., IX, pp. 430-444. See also Annals Applied 



Biology, VII, pp. 11-24. 

 Fellers, C. R., and Allison, F. E. (1920). "The Protozoan Fauna 



of the Soils of New Jersey," Soil Science, IX, pp. 1-26. 

 Goodey, T. (1916). "Further Observations on Protozoa in Relation 



to Soil Bacteria." Proc. Roy. Soc, B, LXXXIX, pp. 297-314. 

 Kent, W. Saville. (1880-82). "A Manual of the Infusoria." 3 vols. 

 Kopeloff, N., and Coleman, D. A ('1917). "A Review of Investi- 

 gations in Soil Protozoa and Soil Sterilization," Soil Science, 



III, pp. 197-269. (Useful Bibliography.) 

 Martin, C. H. and Lewin, K. R. (1915). "Notes on Some Methods 



for the Examination of Soil Protozoa," Journ. Agric. Sci., 



VII, pp. 106-119. 

 Russell, E. J. (1921). "Soil Conditions and Plant Growth," 



London. 406 pages. (See especially pp. 288-294 and Biblio- 

 graphy.') 

 Stead, A. (1920). "The Agriculture and Soils of the Cape Province 



(Witkop-Burghersdorp)." Union of South Africa, Dept. of 



Agric. Reprint, No. 40, Pretoria, 48 pages. 

 Waksman, S. A. (1916). "Studies on Soil Protozoa," Soil Science, 



I, pp. 135-152. See also Ibid., II, pp. 363-376. 



WILD BIRDS AND BILHARZIASIS. 



BY 

 P. W. FlTzSlMONS, 



Director, Port Elizabeth Museum. 



Read July 11, 1921. 



In the past much has been written in reference to water- 

 frequenting birds being responsible for carrying the ova of fishes 

 in mud adhering to their feet. This was accepted as the solution 

 of the incidence of certain species of fish being found in pools and 

 ponds where the water dried up in times of drought. It is now 

 known that these fishes have evolved special powers of survival by 

 burying themselves, in mud, and lying dormant. It has been 

 shown, also, that the eel can travel overland from pool to pool. 



The hypothesis which has now been advanced, that birds 

 carry young snails on mud adhering to their toes, is a plausible 

 one; but like many hypotheses, when thoroughly investigated, it 

 has been found to be erroneous. For twenty-five years I have 

 made a careful study of South African ornithology, especially its 

 economic side, both in the field and in the laboratory. At various 

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