460 THE UNIVERSE. 



of the Cacti is sometimes surrounded with five hundred 

 husbands. 1 



It is even observed that nature multiplies her resources 

 further in order to insure the reproduction of plants when 

 the sexes reside each in a separate flower, and sometimes 

 on plants separated by a great distance. The corollas with 

 stamens produce an enormous quantity of pollen dust, 

 which makes up for the difficulty of communication. This 

 strikes every observer who is in the neighborhood of a 

 pine-forest. The pollen is often borne away from the trees 

 in such abundance that it covers all the surrounding coun- 

 try with its yellow dust. This is the phenomenon known 

 by the name of " sulphur-rain." And, indeed, owing to its 

 yellow color and the way in which it burns with a bright 

 flame, pollen has been thought akin to sulphur by some in- 

 experienced observers. Sometimes when it falls upon the 

 roofs of the neighboring towns, it tints them all over with a 

 pale yellow. 



At the moment when the curtains of the nuptial couch 



1 When a grain of pollen has fallen upon the stigma, and is retained by the 

 hairs projecting from the surface, a pollen tube is emitted, apparently owing to 

 endosmotic action between the fluid exudation from the stigma and the contents 

 of the pollen cell, which latter bursts and sets free the inner lining of the cell in 

 the form of a cylindrical tube. This tube passes down between the cells of the 

 style, lengthening out till it at last reaches the ovules in the cavity' of the ovary. 

 This lentrtheninor was at one time thought to be merely extension, but is now 

 supposed to be due to actual interstitial growth. Having arrived here, the pol- 

 len tube enters the foramen at the top of the ovule left by the imperfect closing 

 of its investments, and thus comes in contact with the nucleus and embryo-sac. 

 In this sac there are at the top some minute vesicles called the germinal vesicles, 

 one or sometimes two of which, under contact, lengthen out into a slender cellu- 

 lar thread, and at one end of this thread is the embryo-plant. The Life of a 

 Seed, by Maxwell T. Masters, M. D. Tr. 



