LABORATORY STUDIES OF CRYPTOGAMS 161 



how the mold grows. Especially notice the growth on the bottom of 

 the dish where the fungus is spreading away from the bread. Make 

 a much enlarged drawing to show the groups of stalked sporangia as 

 seen from the side. Are these groups connected in any way ? Are 

 there any special organs for attachment to the substratum ? Is the 

 number of sporangia in a group constant? Estimate the height of 

 the sporangial stalks in inches. State the magnification which your 

 drawing represents. 



367 (Compound). With a needle carefully remove a bit of the 

 plant, selected from a spot where both white (young) and black (old) 

 fruiting heads (sporangia) can be seen, and mount in water, or better 

 in alcohol followed by a drop of water. Use first a low power, after- 

 wards a higher power. Have the threads partitions? What is the 

 color and appearance of the contents? Compare an unopened spor- 

 angium with one where the external membrane has given way. 

 What portion of a whole head is occupied by spores? Answer by 

 drawings ; show one of the spores separately, more enlarged. 



368 (Compound). If material is furnished, draw two or three 

 stages to illustrate zygospore formation. 



369 (Compound). Water Molds: Saprolegnaceae. — Upon what is 

 the given plant growing? Reinove a bit with forceps and needle to a 

 drop of water on a slide. Examine with the hand lens, to get an idea 

 of the actual size. Then use low and high po^vers of the microscope. 

 Are the hyphse of even diameter? Is the protoplasm dense or thin? 

 What is the shape of the ends of the hyphse? Answer these questions 

 in drawing. 



Do you find certain branches filled with denser protoplasm, and 

 somewhat enlarged or club-shaped? Can j'ou find stages leading 

 to this condition ? Are the swollen extremities (zoosporangia) sepa- 

 rated by a partition from the rest of the hyphae? Find zoosporangia 

 in which the protoplasm seems gathered into many definite masses ; 

 others empty, with these masses (zoospores) escaped, but still near 

 by. From what point do the zoospores escape? Draw an unopened 

 zoosporangium, and one ruptured, together with a mass of the spores. 



370 (Compound). Short-stalked, globular organs (slightly re- 

 sembling the sporangia of Bread ]\Iold) will probably be found in 

 abundance in both old and young stages. Are the youngest ones cut 

 off by a wall? The oldest? What difference in the contents at the 

 two different stages ? You may find gradations from one condition to 

 the other. The organs are the oogonia, and when mature contain a 

 number oi oospores. How many? Have the oospores walls? If so, 

 are they thicker or thinner than walls (if any) of the zoospores 

 before noted? 



371 (Compound). Look for slender branches wath ends applied 

 to the oogonia, and somewhat swollen at the point of contact. In 



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