BOOKS AND CURRENT LITERATURE 79 



are injurious or not is taken up in another paper. "' The author finds 

 that the permeabihty can be either increased or decreased by treat- 

 ment with proper sohitions, and that the tissue soon regains its normal 

 permeabihty upon Ix'ing returned to its original medium, sea water in 

 this case. If the tissue is repeatedly transferred from a solution that 

 decreases to one that increases permeability, and back again, being 

 finally l)rought into sea water, it regains its normal condition without 

 any apparent injury — E. S. Johnston. 



Endemic Floras and Evolution. — When the various theories of 

 evolution are put to the test of interpretation of facts in nature the 

 result is generallj'^ inconclusive and unsatisfactory. A notabl ex- 

 ception is offered b}^ the work of Willis upon the endemic species of 

 Ceylon, which are 809 in number, out of a total plant census of nearly 

 three thousand spQcies.^ Twenty-three of the 324 genera are of strictly 

 Cingalese distribution; six families of seven species each are entirely 

 endemic; four families with a total of 102 species have 91 of them 

 endemic, and 14 families containing a total of 435 species include 255 

 which are endemic. 



In connection with a discussion of the distributional relationship it 

 is shown that many of these species are extremely localized. Thus 

 Coleus elongatus is represented by not more than a dozen individuals 

 on a mountain top, and over a hundred of the endemics are similarly 

 restricted in occurrence, and the group as a whole constitute the rarest 

 plants of the island. 



Dr. Willis points out that the various features of occurrence of the 

 endemics constitute ''an insuperable objection to the theory of natural 

 selection and adaption." Thus the local species of Ceylon are the 

 rarest, which should not be the case if they had developed in response 

 to local conditions. On the contrary, the author holds that the en- 

 demics, as species of local origin, have developed quite indifferently 

 to local conditions. It is concluded that this sensationally large 

 number of endemics owes its origin to mutations which may be almost 

 of generic amplitude. Thus the endemic species do not show any close 

 similarity to their nearest relatives, a fact which the reviewer has 

 previously noted in endemics of the Salton region. — D. T. MacDougal. 



^ Osterhout, W. J. V., Extreme alterations of permeability without injury. 

 Bot. Gaz. 59:242-253. 1915. 



'Willis, J. C. The endemic flora of Ceylon, with reference to geographical 

 distribution and evolution in general. Phil. Trans. Roy Soc, Lond., Ser. B, 

 206, pp. .307-342. 1915. 



