LESSONS IN BOTANY. 205 



On the under side of some leaflets note the crescent-shaped sori, 

 find out if there is any law as to which leaflets carry sori. After 

 soaking in water open a sorus, and note what forms the cover, 

 called the indusium. The yellowish spheroidal bodies in the sorus 

 are the sporangia, notice that they are attached to the veins of 

 the leaflet. Study a sporangium noting its shape, stalk, and the 

 ridge, called the annulus, extending part way round it. Burst a 

 sporangium and note the minute bodies called spores. The spor- 

 angium is opened by the straightening of the annulus; place some 

 sporangia that have been soaked in water on a piece of glass, 

 watch them through a lens, noting the process of opening. Make 

 a diagram of the mode of branching, and write out a description 

 of what has been observed. A larger fern might be more interest- 

 ing and easier to examine in some respects. The same general 

 plan can be followed in examining any fern. 



Such a study gives one some idea of the gross anatomy of the 

 fern and is full enough for purposes of classification. For classi- 

 fication the maiden-hair fern Adiantum pedatum is described as 

 follows by Prof. L. M. Underwood : Root, many delicate fibers 

 somewhat matted. Rhizome, scaly somewhat creeping. Stipe, 

 slender, polished, black, forked at base of frond forming two 

 recurved rachises. Frond, roundish in outline, formed of sev- 

 eral pinnse, which branch from the recurved rachises; pinnules 

 unequal sided, oblong or deltoid ; upper margins irregularly lobed, 

 surfaces smooth. Veins, free, several times forked. Sori, borne 

 at the end of the veins on the under side of the reflexed margins 

 of the lobes, which form somewhat kidney-shaped membranous 

 indusia. Sporangia, globose with a nearly complete vertical ring. 

 Spores, too minute for examination with an ordinary lens. 



The germination of fern spores may be studied by sowing them 

 on closely pressed muck, or even on a piece of glass, and keeping 

 them warm and moist. In this way the prothalium may be ob- 

 tained for study. 



The method of veining varies somewhat and often serves as an 

 aid in classification. In many cases the veins are free, that is 

 arising from either side of the midvein they do not unite with 



