TYPES OF CRYPTOGAMS; PTERIDOPHYTES 291 
356. Reproduction in Ferns. —The reproduction of ferns 
is a more interesting illustration of alternation of gen- 
erations than is afforded by mosses. ‘The. sexual plant, 
gametophyte, is the minute prothallium, and the non- 
sexual plant, sporophyte, which we commonly call the 
fern, is merely an outgrowth from the fertilized egg-cell, 
and physiologically no more important than the sporophyte 
of a moss, except that it supplies its own food instead of 
living parasitically. Like this sporophyte, the fern.is an 
organism for the production of vegetative spores, from. 
which new plants endowed with reproductive apparatus 
may grow. 
THE STUDY OF A CLUB-MOSS (LYCOPODIUM) 
357. Occurrence. — Several species of Lycopodium are common in 
rich woods in the northern and mountainous portions of the eastern 
United States. Any species may be studied. 
358. Examination. — Note whether the plant is chiefly erect or 
prostrate and vine-like. Describe the mode of branching. Are the 
leaves arranged flat-wise or equally on all sides of the stem? Describe 
the leaves briefly. Are they all of one kind or do some portions of 
the plant evidently have smaller leaves ? 
Select fruiting specimens and determine the position of the spo- 
rangia. Is the leaf, near whose base each sporangium is situated, like 
the ordinary foliage leaves of the plant? Are the fruiting portions 
of the plant similar in general aspect or different from the rest of 
the plant and raised above it on stalks? Examine the spores. Are 
they all of one kind ? 
If Selaginella is used in place of Lycopodium or for comparison, 
two kinds of sporangia are to be sought, differing chiefly in shape. 
Describe each briefly. Compare the number of sporesin each. The 
larger spores (macrospores) germinate and at length produce pro- 
thallia bearing archegonia, while the smaller produce prothallia 
bearing antheridia. The archegonia, after fertilization, develop each 
