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A TEXTBOOK OF THEORETICAL BOTANY 



counterparts in many unicellular organisms and in some antherozoids of 

 lower plants, but nowhere are they so large or complex as here. 



The body cell divides between the blepharoplasts, and each half produces 

 an antherozoid. Each blepharoplast breaks up into a cluster of granules, 

 attached to a beak which grows out from the nucleus. The latter then 

 rotates, drawing out the cluster of granules into a long spiral band from 

 which thousands of cilia develop. The nucleus enlarges until it occupies 



Archegonial chamber f 

 Archegonial neck 



Jacket layer ,t 



*^ #-,r 









».*^ 



» • 



*"» W^ 



Fig. 732. — Diooti edide. Longitudinal section 

 through the apex of the female prothallus 

 showing a pair of archegonia. 



nearly the whole of the antherozoid cell, the protoplasm of which rounds off 

 and separates from the wall. This breaks down and liberates the contents 

 into the body of the microspore as a fully motile antherozoid (Fig. 733). 

 The male cells begin to move even before their liberation from the antheridial 

 cell and they apparently remain motile for several hours. These antherozoids 

 are the largest of all known male cells. They may reach a size of 250/x x 300/x 

 and are visible to the naked eye. 



Fertilization 



The basal end of the microspore now enlarges and forms an elongated sac 

 which hangs down into the archegonial chamber. It is extremely turgid 

 and contains highly concentrated fluids. Antherozoids will not live in sugar 

 solutions of less than 30 per cent, strength, which indicates what the osmotic 

 potential of the pollen sap must be. The swollen pollen sac bursts under 



