158 



B07ANY. 



there are two rows of small circular dots, one row on either 

 side of the pinna. These are called the ' ' fruit dots, ' ' or sori 

 (a single one is a sorus). If we examine it with a low power 

 of the microscope, or with a pocket lens, we will see that there 

 is a circular disk which covers more or less completely very 



minute objects, usually the 

 ends of the latter projecting 

 just beyond the edge if they 

 are mature. . This circular 

 disk is what is called the 

 indusium, and it is a special 

 outgrowth of the epidermis 

 of the leaf here for the pro- 

 tection of the spore-cases. 

 These minute objects un- 

 derneath are the fruit bodies, 

 which in the case of the 

 ferns and their allies are 

 called sporangia. This in- 

 dusium in the case of the 

 Christmas fern, and also in 

 some others, is attached to 

 the leaf by means of a short 

 slender stalk which is fast- 

 ened to the middle of the 

 under side of this shield. 



262. Sporangia. If we 

 section through the leaf at 



Fig. 132. 



Rhizome with bases of leaves, and roots of the one of the fruit dots, Or if 

 Christmas fern. 



we tease off some of the 



sporangia so that the stalks are still attached, and examine them 

 with the microscope, we can see the form and structure of 

 these peculiar bodies. Different views of a sporangium are 

 shown in fig. 137. The slender portion is the stalk, and the 

 larger part is the spore-case proper. We should examine the 



