179 

 CURRENT LITERATURE. 



Distribution 



Becari, O., The Palms of the Philipine Islands, Philippine Jour- 

 nal of Science XIV No. 3, {March 1910) pp. 295-362, 3PI. 



The author gives a list of the palms of these islands with notes on 

 points of special interest, and descriptions of new species ; and prefaces 

 it with a general survey. The number of species at present known is 

 120, of which about 20 are non-endemic and for the most part belong to the 

 littoral swamps of neighbouring countries. Nearly all the endemic species 

 belong to Malayan genera. The great bulk of the palm flora belong to the 

 genera Piuanga, Areca, Calamus and Dccmero^s. Of the 36 known species of 

 Areca no fewer than 10 are characteristically Philippine ones, and from the 

 occurrance here of closely allied species, and their absence elsewhere, the 

 author considers that Areca catechu acquired its specific characters in these 



islands. 



P. F. F. 



Evolution 



Arber, Agnes, The Law of Loss in Evolution — a paper read 

 before the Linnaean Society No. 7th, 1918 and, abstracted, in Proc. 

 Linn. Soc. Lond. Oct. 1919. pp. 70-78. 



Mrs. Arber in this paper formulates under the name of the' Law of 

 Loss' a principle which appears to have operated in the evolution of plants. 

 By this she means the general rule that " a structure or orgen once lost in the 

 course of phylogeny can never be regained ; if the organism subsequently 

 has occasion to replace it, it cannot be reproduced, but must be constructed 

 afresh in some different mode." As instances of the working of this Law of 

 Loss, though in the nature of things formal proof cannot be given, she points 

 out that certain water-plants, Ceratuphi/llum and Ltricularia sp., are entirely 

 rootless even as seedlings, and since the evidence is all in favour of a terres. 

 trial origin of the Flowering Plants we are driven to the conclusion that these 

 plants have lost the power of producing roots, and that in both the need of 

 an absorbing organ has reasserted itself and has been met, not by the re- 

 establishment of true roots, but by the development of special subterranean 

 shoots which act as roots. Again it seems probable that the Monocoty ledons, 

 derived, as we have good reason now for believing, from a dicotyledonous 

 ancestor, have lost the property of forming a true leaf-lamina, so that their 

 leaves consist of base and stalk, or eyen leaf-base alone ; when an 

 attemt is made to produce a compound leaf, it isiby a totally different method. 

 As another instance she points out that Flowering Plants are considered to 

 have been derived ultimately from a fern-stock in which the male gamete» 

 in harmony with its aquatic life, is ciliated ; but the submerged flowers of 

 present-day phanerogams have merely slightly modified pollen grains which 

 are dependent on currents in the water to find the ovules, the art of producing 

 cilia havingbeen lost. Other instances are the pappus scales of certain 

 Compositte which there is good reason to believe are hairs, not modified sepals, 

 aiuL'Small has given reasons for supposing that this order was derived 



