The Pezizas and related forms are fleshy, and present but little difficulty in fixing, cutting, or staining. They are abundant in moist places, on decaying wood, or on the ground. The apothecia have the form of little cups, which are sometimes black and sometimes fleshcolored, but often orange, red, or green.
For general morphological work it is better to tease out fresh or preserved material. Sections showing the entire ascus should be 10 to 15( in thickness.
For the free nuclear division in the ascus, and also for the development of the ascospores, Flemming's weaker solution, followed by the safranin, gentian-violet, orange combination has given excellent results. The centrosomes, especially at the first division in the ascus, are sharply defined and the radiations are conspicuous. With iron-alum haematoxylin and orange, the nuclear detail and the centrosomes are better, but the spindle and radiations are not so sharply defined. For such details, sections should not be thicker than 5(, and 3( will give a clearer view.
Morchella esculenta is very good for the development of the ascus because the nuclei are very large.
For showing the ascogonium, ascogenous hyphae, and the origin of the asci, nothing is better than Pyronema. Fix in formalin, acetic acid (10 c.c. formalin, 5 c.c. acetic acid, and 85 c.c. water) for 24 hours or more; wash in water and stain in eosin. Or, fix in the special chromo-acetic-osmic solution and stain in iron-alum haematoxylin. In either case, use the Venetian turpentine method and tease the material so as to obtain instructive views.
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