364 THE VIEWPOINT OF A PHYSIOLOGIST 



functional tests of variation and for cellular and enzymatic anal- 

 yses of the ways in which the environment induces phenotypic 

 change. Second, to better understand natural variation and to 

 distinguish nongenetic from genetic differences there is need for 

 careful acclimation experiments on populations collected over the 

 full range of a species, the examination of physiological clines, 

 in experiments extending over complete life cycles. The use of 

 physiological responses to various environmental stresses as cri- 

 teria of natural variation permits a close approach to the key 

 problem of evolution, the development of adapted types of plants 

 and animals, if not to the origin of species. 



REFERENCES 



Adriaanse, M. S. 1947. Ammophila campestris Latr. unci Ammophila 



adriaanus Wilcke. Ein Beitrag zur vergleichenden Verhaltungsfor- 



schung. Behaviour, 1, 1-34. 

 Adolph, E. F. 1943. Physiological Regulations. Jaques Cattell Press, 



Lancaster, Pa. 

 Aird, I., and H. H. Bentall. 1953. A relationship between cancer of 



stomach and the ABO blood groups. Brit. Med. J., 1, 799-801. 

 Aird, I., H. H. Bentall, and J. A. Mehigan. 1954. Brit. Med. J., 2, 315- 



21. 

 Anderson, J. D., and C. L. Prosser. 1953. Osmoregulating capacity in 



populations occurring in different salinities. Biol. Bull., 105, 369. 

 Bates, M. 1949. The Natural History of Mosquitoes. The Macmillan 



Company, New York, N.Y. 

 Blair, W. F. 1955. Mating call and stage of speciation in the Micro- 



lu/la olivacea-M. carolinensis complex. Evolution, 9, 469-80. 

 Biasing, I. 1953. Experimentelle Untersuchungen iiber den Umfang 



der okologischen und physiologischen Toleranz von Planaria alpina 



Dana und Planaria gonocephala Dugcs. Zool. Jahrh. Aht. (dig. Zool. 



u. Phys., 64, 111-52. 

 Boyd, W. C. 1950. Genetics and the Races of Man. Little, Brown and 



Co., Boston, Massachusetts. 

 Brand, T. v. 1952. Chemical Physiology of Endoparasitic Animals. 

 Academic Press, New York, N.Y., Chapters 10, L3, 14. 



