(153) 



are equal; the surface is in two ways locus of points with fixed 

 distance to a given right line (each of the axes). If those two 



distances are equal, - each, the surface divides elliptic space into 



two congruent parts ^). 



Botany. — '■'On the distribution of the seeds of certain species of 

 Dischidia by means of a species of ant : Iridomyrmex niyr- 

 mecodiae Emery.'" By Dr. W. Docters van Lkkuwen and 

 Mrs. J. Docters van Leeuwen — Reynvaan. (Comnuiuicated by 

 Prof. F. A. F. C. Went). 



Schimper ^) in his well-known work on American epiphytes, has 

 arranged these plants in a number of groups according to the methods 

 by which their seeds are distributed. Obviously it is necessary for 

 these plants, that their seeds should ultimately reach the places, in 

 which the adult plants generally grow. The seeds of epiphytes may 

 be distributed through the agency of fructivorous animals, and through 

 that of the wind. The representatives of the first group are characterized 

 by the possession of edible portions of the fruit or seed. Various 

 members of this group are known among the orders Ridjiaceae, 

 Melasiomaceae, Artocarpeae, etc. The wind may distribute the seeds 

 if they are very light, as is the case with Orchids for instance; the 

 spores of epiphytic Lycopodiaceae and Filicinae are also carried 

 from tree to tree by air-currents. Other plants have seeds provided 

 with a floating mechanism such as representatives of Gesneraceac 

 and Asclepiadnceae. 



Among well known epiphytes belonging to the last named order 

 are various species of Dischidia, of which D. Raffesiana has already 

 been dealt with in several works. Since our arrival in Java, we 

 have had repeated opportunities of observing this plant, both in its 

 natural habitat and in our garden. Not only D. Rafflesiana but 

 also D. collyris and still moi-e D. nwnmularia are especially abun- 

 dant in the immediate neighbourhood of our present abode. On the 



1) Likewise we find elliptic space Sin-\-\ of an od<l number of dimensions 

 divided into two congruent parts by the quadratic Qin containing the points at fixed 



distance = j from a given plane Sn as well as from its reciprocal polar Sn with 



respect to ri2». 



~) A. F. W. ScHiMPER. Die epiphytische Vegetation Araorikas. Bot. Milt. a. d. 

 Tropen, Jena 1888. 



