COLLECTION AND PRESERVATION OF MATERIAL. 345 



trunks of trees, in damp situations. They may be preserved in 

 formalin or alcohol. Some of the material may also be dried 

 under pressure. 



Mosses are easily found and preserved. Male and female 

 plants for the study of the sexual organs should be preserved in 

 formalin or alcohol. In all these studies whenever possible living 

 material freshly collected should be used. 



Ferns. 



For the study of the general aspect of the fern plant, polypo- 

 dium, aspidium, onoclea, or other ferns may be preserved dry 

 after pressure in drying sheets. A portion of the stem with the 

 leaves attached should be collected. These may be mounted on 

 stiff cardboard for use. The sporangia and spores can also be 

 studied from dried material, but for this purpose the ferns should 

 be collected before the spores have been scattered, but soon after 

 the sporangia are mature. But when greenhouses are near it is 

 usually easy to obtain a few leaves of some fern when the sporangia 

 are just mature but not yet open. To prevent them from opening 

 and scattering the spores in the room before the class is ready to 

 use them, immerse the leaves in water until ready to make the 

 mounts ; or preserve them in a damp chamber where the air is 

 saturated with moisture. 



For study of the prothallia of ferns, spores should be caught 

 in paper bags by placing therein portions of leaves bearing ma- 

 ture sporangia which have not yet opened. They should be 

 kept in a rather dry but cool place for one or two months. 

 Then the spores may be sown on well-drained peat soil in pots, 

 and on bits of crockery strewn over the surface. Keep the pots 

 in a glass-covered case ^here the air is moist and the light is 

 not strong. If possible a gardener in a conservatory should be 

 consulted, and usually they are very obliging in giving sugges- 

 tions or even aid in growing the prothallia. 



Lycopodium, equisetum, selaginella, isoetes, and other pteri- 

 dophytes desired may be preserved dry and in 70$ alcohol. 



Pines, — The ripe cones should be collected before the seeds 



