760 Botanical Microtechnique 



basidiospores are borne. The texture ot the trama of the fruit body 

 ranges from the soft, fragile pileus of a small Copnnns to the "woody" 

 perennial pileus of Fomes. The softer members are difficult to 

 preserve in normal condition but are easy to section, whereas the 

 leathery fructifications can withstand processing but are very difficult 

 to section. 



The basidia of many species of Agaricaceae have been successfulh 

 fixed in weak chrome-acetic, in Craf III, or in Allen-Bouin II and III. 

 The last is particularly good for cytological details. Bouin's solution 

 has given good results, but it is rather erratic. Dehydrate in alcohol or 

 acetone, beginning with 5*;; and using steps of 5<^; at 15- to 30-min. 

 intervals. Iron hematoxylin and gentian violet-iodine are excellent 

 for nuclear details. Safranin-fast green stains the nuclei well enough 

 and also shows the gill and trama structure. 



Softer members of the Clavariaceae, Hydnaceae, and Polyporaceae 

 are processed as above; the leathery and woody forms must be 

 dehydrated in butyl alcohol or dioxan. Fortunately, basidia mature 

 in the soft new growth in even the toughest perennials. 



Exobasidium occurs on Vaccinium, Rhododendroyi, and other 

 members of the heath family. Kill in FAA or Craf III. Because of the 

 U'athery texture of the host the use of butyl alcohol is advisable. 



FUNGI IMPERFECT! 



This category includes fungi for which the perfect or sexual stage 

 has not yet been found. The perfect stage, w^hen discovered, is found 

 to Ijc a basidial or ascigcrous stage, and the organism is ihcii 

 transferred to the ajjpropriate group. Sporulation is l)v conidia. 

 produced either at random on tlie mycehum or in ck)sed pycnidia. 

 The vegetative mycelium may be a sujK'rlicial saj)r()pliytc. a 

 saprophyte within dead tissues, or a parasite within tissues. 



Mycelium and conidia from cultines can l)e prepared as whole 

 mounts by the general methods outlined in Chap. 10. Parasitic species 

 are handled in accordance with the properties of the organ on \\hi( h 

 they occur. Leaf parasites are the easiest to handle. I'he h)llowing 

 illustrations are selected from successful j)reparations of important 

 fimgi. 



Diphxlid zeae grows readily in agar culture and jn-oduces 

 abundant pycnidia. Can out small pieces of agar bearing ihe pycnidia, 

 fix in Craf I, and embed in paraffin. A heavy overstain in hemalum, 

 slightly dillerentiated in HC:i. stains the hvaline portions of the 

 fungus \erv well. The pvcnidia and the mature spores ha\e 

 consideral)le pigmentation. 



