254 



SEEDLESS PLANTS 



almost everywhere. City schools can supply themselves with speci- 

 mens by cultivating a few ornamental ferns in the schoolroom. While 

 gathering specimens look along the ground under the fronds, or in 

 greenhouses where ferns are cultivated, among the pots and on the floor, 

 for a small, heart-shaped body like that represented in Figures 493, 494, 

 -called a.prothallium. It is found only in very wet places and care must 

 be taken in collecting specimens, as in their early stages the prothalli 

 bear a strong resemblance to certain liverworts found in the same 

 places. The best way is for each class to raise its own specimens by 

 scattering the spores of a fern in a glass jar, on the bottom of which is 

 a bed of moist sand or blotting paper. Cover the jar loosely with a 

 sheet of glass and keep it moist and warm, and not in too bright a light. 

 Spores of the sensitive ferns (Onoclea) will germinate in from two to 

 ten days, according to the temperature. Those of the royal fern 

 {Osnmnda) germinate promptly if sown as soon as ripe, but if kept 

 even for a few weeks are apt to lose their vitality. The spores of 

 sensitive fern can be kept for six months or longer, while those of the 

 bracken (Pterts) and various other species require a rest before ger- 

 minating, so that in these cases it it better to use spores of the previous 

 season. 



360. Study of a Typical Fern. Observe the size and 

 general outline of the fronds, and note whether those of 

 the same plant are all alike, or if they differ in any way, 

 and how. Observe the shape and texture of the divisions 

 or pinnae composing the frond, their mode of attachment 

 to the rhachis, and whether they are simple, or notched or 

 branched in any way. Make a sketch, labeling the pri- 

 mary branches of the frond, pinna (sing, pinna}, the 

 secondary ones, if any, pinnules, and the common stalk 

 that supports them, stipe. Note the color, texture, and 

 surface of the stipe. If any appendages are present, such 

 as hairs, chaff, or scales, notice whether they are most 

 abundant toward the apex or the foot of the stipe, or 

 equally distributed over its whole length. Cut a cross 

 section near the foot and look through your lens for the 

 roundish or oblong dots that show where the fibrovascular 

 bundles were cut through (Fig. 482). How many of them 

 do you see ? Make a sketch and compare with your sec- 

 tional drawings of the stems of monocotyledons and 

 dicotyledons ; what differences do you notice ? Which 

 does it resemble most ? 



