Simple Plants 209 



Sexual reproduction occurs when one or more large oval protrusions 

 form on branches which have grown out apparently for this purpose. 

 At the very end of this branch is the terminal cell in which many small 

 cells are formed. These small cells escape into the water. Each one 

 possesses long cilia by means of which it swims about. A single one 

 of these ciliated forms enters the oval mass. The little ciliated form 

 is known as the male gamete, and the large oval protrusion as the 

 female gamete. The organ which produces a gamete is called a gonad 1 

 ( ). The oval body is consequently known as an 



oogonium ( ) or egg-gonad. Two gametes, uniting 



as have the two just mentioned, form a single cell known as an oospore. 

 This oospore, after a short period of rest, forms a new plant. It will 

 be noted that in vaucheria the gametes are of unequal size. In spirogyra 

 they were of equal size. In fact, whenever gametes are formed, it is 

 the smaller and more active one, regardless of whether there are any 

 other distinguishing features or characteristics, which is called the male 

 gamete or sperm, while the larger and more passive one is known as the 

 female gamete or egg. 



The union of sperm and egg is called the process of fertilization. 



The male gonad is called the antheridium ( ), 



and the female gonad is known as an oogonium. 



Some algae live with various fungi. These symbiotic ( ) 



plants are the lichens ( ) (Fig. 96). 



THE FUNGI 



The Algae-like, or tube fungi, make up the Phycomycetes, while the 

 higher fungi, such as mushrooms, toad-stools, puff-balls, rusts, and smuts, 

 are known as Carpomycetes. 



The fungi, no matter how differently they may appear or in what 

 out-of-the-ordinary place they may grow, are alike in two great char- 

 acteristics : 1. They possess no chlorophyl, and 2. They reproduce by 

 spores. 



They live either upon decaying matter, in which case they are called 

 saprophytes, or at the expense of another organism when they are called 

 parasites. 



Bread Mold is easily obtainable, but that from fruits or from dead 

 flies serves just as well for study (Fig. 98). There is a tangled mass 

 of thread-like structure which is the working body of the plant. This 

 tangled mass is known as mycelium ( ), while the 



individual threads are known as hyphae ( ). If the hyphae 



send out threads in turn, these are called rhizoids ( ), 



and these little root-hairs penetrate the substance on which the mold 

 forms and through which it absorbs what is needed. It is supposed 



1 Botanists do not look with favor on the term "gonad" in plants, but it has seemed advisable 

 to use this term here, for, in zoology the student must use it constantly. 



