428 PHYSIOLOGY OF THE FUNGI 



when compared with that on a control medium, is cjuite satisfactory. 

 Thus, if the growth and sporulation (if any) of each fungus on medium 4 

 are arbitrarily given the values of 4 + , the estimated abundance on other 

 media may be designated as greater or less than 4, as the case may be. 

 Such a rough method has been found satisfactory for illustrating principles 

 and determining the availability of carbon sources utilized by the fungi. 

 If a more accurate measurement is desired, liquid media should be used 

 and dry weights of the mycelia obtained. Observations and records 

 should be made on any other characteristics which are affected by changes 

 in carbon source. 



List of test fungi: Aspergillus rugulosus, Ceratostomella fimbriata, 

 Dendrophoma obsmrans, Endothia parasitica, Glomerella cingulata, Guig- 

 nardia bidwellii, Melanospora sp., Monilinia friicticola, Phycomyces 

 blakesleeanus, Pleurage curvicolla, Sordaria Jimicola, Sphaeropsis malonan, 



Ustilago striiformis. 



EXERCISE 5 



The Effect of the Nitrogen Source on Growth and Sporulation 



The purpose of this exercise is to illustrate the utilization of different 

 sources of nitrogen by different fungi. This exercise should follow soon 

 after Ex. 4, and the procedure should be the same. The use of some of 

 the same test fungi in this exercise should emphasize the importance of a 

 suitable semisynthetic medium for growth and reproduction. In this 

 case the carbon source (glucose) shall be kept constant and the nitrogen 

 source varied with each medium. The other constituents of the basal 

 medium will be the same as listed under Ex. 4. Medium 1 may again 

 be used as a control, but if a different lot is made, it must carry a new 

 number. 



Media 



The amount of nitrogen should be kept constant. The weights of the 

 compounds used should be calculated to contain a weight of nitrogen 

 equivalent to that in 2 g. of asparagine. 



EXERCISE 6 

 Special Nutritional Conditions Which Influence Growth and Sporulation 



The two previous exercises have dealt mainly with the effect of the 

 constituents of the medium on a qualitative basis (see Chaps. 3 and 14). 

 This exercise is outlined to emphasize some of the effects of quantitative 



