162 LABORATORY STUDIES OF CRYPTOGAMS 



some cases these branches (antheridia) may send tubes into the 

 oogonia. The antheridia may grow from the stalks of the oogonia 

 themselves, or from the main hyphae close by. 



Draw old and young oogonia, with contents, and antheridia (if 

 found). 1 



372 (Simple). Peziza. Upon what as a substratum does the spe- 

 cies of Peziza furnished grow ? If the Peziza is small, use the hand 

 lens in examination. What is the general shape? Is the external 

 surface entirely smooth ? Is the color the same on inner and outer 

 surfaces? Represent all features of form in a drawing considerably 

 larger than nature, if necessary. 



373 (Compound). Cut sections perpendicular to the inner sur- 

 face. Mount in water. Do you find, with a high power, elongated 

 sacs containing a definite number of rounded bodies (spores) ? Do 

 you find many or few such sacs? (If the sections are not very thin, 

 press the cover glass down cautiously with a needle to spread them out 

 thinner.) How are they situated relatively to one another and to the 

 surface of the plant ? They are near which surface, inner or outer ? 

 How many spores in each sac, or ascus? Draw a diagram of the Peziza 

 in section, showing the region of the sacs, and indicate some of the 

 sacs in position. Draw a sac (ascus) highly magnified, with spores, 

 and the threads that grow up between the sacs. 



374 (Compound). Pulling off with forceps bits of the substratum 

 at the point where the cup of the Peziza was attached, and spreading 

 these bits out with needles in water on a slide, you may find the 

 threads of the fungus, which gather nourishment from decayed vege- 

 table matter. These threads together form the mycelium ; the sau- 

 cer-shaped or cup-shaped sac-bearing body first examined is the 

 apotheciunr. That layer of the apothecium in which the sacs are 

 found is the hymemum. Label drawings according to the terms given. 



375 (Simple). Microsphsera. 2 With the lens examine the whit- 

 ened patches of the fungus-infested leaf. Is the whitening external 

 or internal? To decide this, wet the leaf with a drop of alcohol, and 

 scrape gently with a knife point. The black, rounded bodies are 

 perithecia. Indicate by drawing the size of the leaf and of the peri- 

 thecia. Wet a bit of the fungus with alcohol, and remove with a 

 knife to water on a slide. If the material has been dried, add strong 

 potash solution to the preparation. Is the white film composed of 

 granules or of threads ? Examine the perithecia by transmitted 

 light. Have they appendages ? Draw a perithecium much magni- 



1 In the same mount more than one kind of Water Mold may be 

 found, the species differing in position and character of oogonia, and in 

 antheridia and sporangia. 



2 Or any genus of the group Erysiphece ; perhaps the commonest form 

 being Microsphcera alni, the cause of mildew on Lilac leaves. 



