252 Field, Forest, and Wayside Flowers 



The prothalli of the adders'-tongues and of the 

 club-mosses are generally tuberous, and grow half 

 buried in the soil, or beneath its surface. Those 

 of the ferns and horsetails are green and leaf-like. 

 But all are alike short-lived; all are quite destitute 

 of woody tissue, and all are very small in com- 

 parison to the parent-plant. 



The spores shed by the largest of our native 

 ferns develop into prothalli less than half an inch 

 wide in their widest part. They lie pressed close 

 to the surface of the ground, or sometimes beneath 

 it, and being so tiny and so retiring in their habits 

 it is difficult to find them. 



A pot in which a fern-plant has come to matur 

 ity and shed its spores, will probably contain some 

 growing prothalli, and we may be able to find them 

 by careful turning over of the surface-soil. But 

 the details of their structure can be studied only 

 by aid of a microscope of four or five hundred 

 diameters. 



By use of the lenses we have learned that after 

 the prothallus has "got its growth," two sets of or- 

 gans appear upon its under surface. These fill the 

 same place in the history of the fern that stamens 

 and pistils do in the history of the flowering 

 plant. They are called antheridia and archegonia. 



