166 Botanical Microtechnique 



Isoetales 



Young sporangia of Isoetes arise on small sporophylls closely 

 apjjrcssed to the rhizophore. Dissect away the sporophylls under a 

 binocular, trim off much of the sporophyll, and kill the sporangia in 

 medium chrome-acetic or FA A. 



The large sporophylls and mature sporangia are inadequately 

 represented by sections. To section mature spores, cut the sporangia 

 away from the sporophylls, drop the ruptured sporangia into a 

 centrifuging tube of FA A. Process in butyl alcohol, centrifuging the 

 mass after each change. Much tearing of the spore wall can be 

 expected during sectioning. 



The preparation of gametophytes should be undertaken only after 

 a study of research literature in which methods are given for 

 germinating and processing the material. 



Equisetales 



Equisetian cones differentiate underground during the late siunmer 

 and contain mature spores when they emerge from the ground the 

 following spring. Young strobili should be dissected away from the 

 rhizome, thoroughly washed, divided into several pieces, and killed 

 in medium chrome-acetic or FAA. Both transverse and longitudinal 

 sections should be made. There is little excuse for sectioning strobili 

 containing mature spores. Compared w'ith a dissection under a 

 binocular, a section presents an lUterly inadequate pictiue of the 

 interesting organization of the cone. Mature spores should be studied 

 in a wet mount, which is subsequently uncovered and permitted to 

 dry, bringing about the uiKoiling of the elaters. 



Gameto{)hytes can be grown by sowing ne^vh shed spores on 

 sterilized sphagnum. Excellent ])reserved gametophvtes also can be 

 purchased. Embedding and sectioning arc carried oui as with other 

 soft, delicate subjects. 



Ophioglossales 



Bolryclniun is the easiest member of this order to use for the study 

 of reproduction. The sporoj)hylls can be teased aj)ai t and crushed to 

 determine the stage of sporogenesis. Subdivide the fertile frond into 

 small pieces, and kill in medium chrome-acetic or Craf II. A wide 

 \ariety of stains will produce brilliant preparations. 



Collectors find gametophytes to be extremely abundant in localized 

 areas dining favorable seasons. Preserved game lophytes can be 

 purchased and are easy to process. 



