218 



General Biology 



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

 because the entire protoplasm is 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 of Spagnum 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 branches) 

 and the archegonia (female branches) (Fig. 111). In some species, 



Fig. 111. 

 A Common Moss 

 (Polytrichum 



commune). 

 A, male plant, 

 showing cup-like 

 tip containing the 

 antheridia. B., fe- 

 male plant with 

 the sporophyte; 

 cal., 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 

 the Tip of the 

 Male Plant of a 



Moss (Funaria). 

 a., antheridium; 



/., sterile filament, 



or paraphysis; /., 



leaf. 



Section Through 

 the Tip of a 

 Female Plant of 

 a Moss (Funa- 

 ria) . 



A., group o£ 

 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, 

 sion of Ginn & Co., Publishers.) 



by permis- 



entire 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. 1 (Fig. 112.) 

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



1 Botanists use "sperms" for the plural of "sperm," while zoologists do. not. We have r there- 

 for, kept the term "sperm" throughout as meaning both singular and plural. 



