214 APPENDIX. 



for the most part, easy, but demands much time. If time al- 

 lows, cross-sections of roots may be made and mounted in balsam. 

 They are readily cut in pith. Sections of the rhizome may be 

 made freehand with a razor or, better, with a microtome : but 

 the old stems are exceedingly hard and liable to injure the 

 knives. 



The Frond or Zew/' may be obtained in fruit in July and 

 August and preserved in alcohol. From it sections of leaflets 

 may easily be got by imbedding in pith. Epidermis is obtained 

 with some difficulty (by beginners) after scraping. Fresh fern- 

 leaves from hothouses answer the purpose as well, are easier to 

 get, and more attractive. Really good sections of fern-leaves are 

 not easy for beginners to make. They should be kept on hand. 



Sporangia may be obtained in abundance from alcoholic 

 specimens of Pteris, or upon hothouse ferns, even in midwinter. 

 Some of the many species of Pteris found in hot-houses answer 

 every purpose. The thin edge of a scalpel slipped under the un- 

 ripe indusium removes the latter, and generally also long ranks of 

 sporangia in all stages of development. In some sporangia spores 

 may be found. Sporangia and spores are always readily got, 

 but care must be taken to select fruit-dots which are not too old 

 or too young. 



Sprouting the Spores. To obtain good specimens of sprout- 

 ing spores and pYOthallia, free from dirt, we can recommend the 

 following procedure : Fill several small flower-pots, which have 

 been thoroughly cleaned inside and out, with clean line sand. 

 Sterilize the whole by baking in an oven or a hot-air sterilizer. 

 Set the pots into large (porcelain) dishes capable of holding water, 

 .and keep the bottom of these dishes covered to the depth of one 

 inch with water; cover the pots completely with bell-glasses. 

 After twenty-four hours, or after the sand and the pots have be- 

 come thoroughly wet, inside and outside, dust thickly the sand 

 tfnd the outsides of the pots with spores (obtained from fern- 

 houses by shaking fertile fronds over white paper). Care must 

 be taken to get spores, and not merely empty sporangia. After a 

 week or longer (sometimes several weeks) a bit of the surface- 

 layer of sand is removed to a drop of water on a slide and exam- 

 ined for sprouting spores. These will often be found in various 

 stages of development. After a month or two prothallia will ap- 



