CRYPTOGAMS 



345 



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

 bear a strong resemblance to certain liverworts found in the same situa- 

 tions. The best way is for each class to raise its own specimens by scat- 

 tering 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 (Osmunda) ger- 

 minate 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 (Pteris) and various 

 other species require a rest before germinating, so that in these cases it 

 is better to use spores of the previous season. 



402. 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 com- 

 posing the frond, their 

 mode of attachment to 

 the rachis, and whether 

 they are simple, or 

 notched, or branched in 

 any way. Hold a pinna 

 up to the light and notice 

 the veining. Is it like any 

 of the kinds described in 

 171, 172? In what re- 

 spect is it different? 

 This forked venation is 

 a very general character- 

 istic of ferns. When the 

 forks do not reticulate or 



intercross, the Veins are FIGS. 487-491. A fern plant: 487, fronds 



j , i f ,1 and rootstock; 488, fertile pinna: s, s, sori ; 



Said to be tree; are they 489, cross section of a stipe, 'showing ends of the 



free in VOUr specimen Or fibrovascular bundles; 490, a&uster of sporangia, 



magnified ; 491, a single sporangium still more 

 retlCUlated: Make a magnified, shedding its%x>res. 



