How to Study Them. 55 



a leafy frond, so we proceed to B as indicated at the right hand 

 margin. There being an indusium present, we are directed to C, 

 where we find four statements. Our fern agrees with the second, 

 as the indusium is formed of a reflexed portion of the frond. 

 Passing to D we find it agreeing with the first statement. Passing 

 to E the statement, "Sporangia at the ends of the veins, borne 

 on a reflexed portion of the margin of the frond," answers our 

 purpose, and the marginal reference, VI., refers us to the genus 

 numbered VI., Adiantum. Under this genus we find two state- 

 ments designated by *, and ^^^ ; the latter referring to the " dichot- 

 omously forked " fronds, answers our purpose, and we find our 

 fern to be number 5, Adiantum pedaium, L., the scientific name 

 of the Maidenhair, which we can now place in our description. 

 Turning to the glossary of technical terrhs we find the applica- 

 tion of the generic name ; in the glossary of specific terms we 

 find the application of the naxne pedatum. Were we in Florida or 

 any of the Southern States, instead of A. pedatum we would 

 probably have found the Venus' Hair {A. Capillus- Veneris), or in 

 California the Californian Maidenhair (A. emarginatum) either 

 of which would agree with the common Eastern species in all 

 respects save the method of branching of the frond and the 

 shape of the pinnules. In like manner we can trace any of our 

 native species to their scientific names, by carefully noting their 

 structure and methods of fruiting. 



log. In a few ferns it will be necessary to exercise great care 

 in the examination of the indusia. In the genera Cystopteris, 

 Dicksonia and Woodsia^^xvd, in a few species oi Aspidiumth^ indusia 

 wither away after fruiting, so that one is likely to classify them 

 under the non-indusiate genera if he carelessly examines them in 

 this condition. In such cases a large number of sori should be 

 carefully examined and the least trace of an indusium should be 

 noted. Five-sixths of our genera, including four-fifths of our 

 species, are indusiate. 



no. Histology. The minute structure of the ferns will fur- 

 nish unlimited opportunity for observation with the highest mag- 

 nifying powers of the compound microscope. Sections for exam- 

 ination should be shaved very thin with a razor or with knives 

 made for the purpose, so as to be transparent, otherwise they 

 must be illuminated from above by a condenser or stage mirror. 

 In this way sections of stipes, foliage, epidermis or sori can be 

 examined to advantage, illustrating the various forms of tissue. 

 The scales, hairs, tomentum, and glands of various species will 



