PLANT WORLD CONTINUED 



211 



As the leaves mature, a goodly portion of the cells increase in size, 

 the entire protoplasm being added to the walls of the cell so that these 

 become very thick. This leaves the cell filled with nothing but air and 

 water. In fact, this hygroscopic ( ) ability of the 



cells is the reason florists use the sponge-like Sphagnum in packing 

 flowers for shipment. 



In those branches which are set aside for reproductive purposes, 

 each sex uses individual branches for the antheridia (male branch) and 

 the archegonia (female branch), (Fig. 111). In some species, entire 



Fig. Ill 



A Common Moss 

 (Polytrichum 

 commune ) . 

 A., male plant, 

 showing cup-like 

 tip containing the 

 antheridia. B., fe- 

 male plant with 

 the sporophyte ; 

 col., cap, or calyp- 

 tra, over the de- 

 veloping spore 

 case ; C., a. mature 

 spore case with 

 the calyptra re- 

 moved. 



Antheridia and Archegonia. 

 Section Through Section Through 



the Tip of the the Tip 



Male Plant of a 

 Moss ( Funaria ) . 



a., antheridium ; 

 f., sterile filament, 

 or paraphysis ; I., 

 leaf. 



the Tip of 

 Female Plant of 

 a Moss (Funa- 

 ria). 



A., group of 

 archegonia a. ; I., 

 leaf. B., an arche- 

 gonium in detail, 

 showing enlarged 

 basal portion e. 

 with the egg, and 

 the neck n. above 

 with its row of 

 canal cells ; m., 

 mouth. (After 



Sachs.) 



(From Bergen & Davis' "Principles of Botany," by permis- 

 \ sion of Ginn & Co., Publishers). 



plants are of one sex or the other. In these, therefore, antheridia and 

 archegonia are never found on the same plant. Such plants are said to 

 be dioecious (from two households), while those plants on which both 

 male and female reproductive branches appear are said to be monoecious 

 (from one household). 



The branches bearing antheridia are called antheridophores. An 

 antheridium is found in the axil ( ) of each leaf of the 



head and consists of a stalk composed of not more than four rows of cells. 

 When the antherium is mature it contains many sperm.* (Fig. 112.) 

 The sperm are coiled, and bear two long thread-like cilia at their anterior 



*Botanists use 

 for, kept the term 



'sperms" for the plural of "sperm," while zoologists do not. We have, there- 

 'sperm" throughout as meaning both singular and plural. 



