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. 
