706 SUMMARY OF CURRENT RESEARCHES RELATING TO 



What is a Species ? — S. W. Williston * says that there is no answer 

 and never will be any answer to the question, What is a species? 

 which lias been asked continuously since the time of Linne. " As we have 

 long since learned that species, like Topsy, just ' grew,' we have and 

 always shall have as great difficulty in deciding when varieties and races 

 become species as we have in determining when a puppy becomes a dog 

 or a lamb a sheep." 



" The only biological entity is the individual, and the individual is 

 inconstant." ..." Accumulated heredity may outweigh natural selec- 

 tion or environment, and vice versa." ..." New phyla arise from 

 crescent phyla, never from decadent or even dominant ones." . . . 

 "Senility and decadence are the attributes of species, families, and 

 orders, as well as of the individual." ..." The older the genus or 

 allied group of species, the more restricted, apparently, is fertile 

 hybridity." ..." Secondary sexual characters are transmitted to the 

 opposite sex, unless of positive disadvantage." ..." Secondary sexual 

 characters are more numerous and less stable in the male than in the 

 female." ..." An organ once functionally lost is never permanently 

 regained." . . . " Gigantism is an indication of approaching decadence." 

 ..." FertUity depends chiefly upon the inheritance of physiological 

 characters." 



The author is a taxonomist who has named and described a thousand 

 or more species. What rules has he ? " Forms of animals which 

 present distinct assemblages of characters, in form, colour, and arrange- 

 ments of parts under natural conditions, which are recognisable from 

 descriptions and figures, should receive distinctive names and be 

 catalogued, provided, of course, that the assemblage of characters 

 includes all ontogenetic changes. If, in the examination of abundant 

 material from different natural environments, we find these characters 

 fairly constant, the forms may properly be called species, if not varieties 

 or races." 



Functions of Membranes.f — H. Zangger has made a study of the 

 role of membranes in normal and abnormal functioning. He discusses 

 the formation and critical thickness of membranes, the reversible and 

 irreversible changes in permeability, and similar questions, showing how 

 very important membranes are in the economy of the body. 



New Horse from Lower Miocene.^ — F. B. Loomis describes Para- 

 hippus tyleri sp. n., closely related to P. nebraskensis, which helps to fill 

 in part of the gap between the rich Oligocene Mesohippus fauna and the 

 Upper Miocene Protohippus group, just where the transition from the 

 Brachydont uncemented teeth to the Hypsodont cemented ones occurs. 



Occasional Luminosity of White Owl.§ — R. J. W. Purely brings 

 forward the testimony of many observers in North Norfolk to the effect 

 that two birds in the district — almost certainly owls (Strix flammed) — are 

 occasionally luminous. 



* Amer. Nat., xlii. (1908) pp. 184-94. 



t Viert. Nat. Ges. Zurich, lii. (1908) pp. 500-36. 



J Amer. Journ. Sci., xxvi. (1908) pp. 163-4 (1 fig.). 



§ Trans. Norfolk and Norwich Nat. Soc, viii. (1908) pp. 547-52. 



