420 PHYSIOLOGY OF THE FUNGI 



only for the laboratory work in this course. The student should take 

 notes and record data so that anyone familiar with the subject could 

 organize the data and write an intelligent summary. Data taken during 

 the experiments are important and in themselves may be quite convincing 

 at that time, but data alone without organization and discussion of their 

 meaning are often sterile and soon forgotten. 



The paper should be written as soon as possible after the termination 

 of the laboratory exercise. It is suggested that all students read the 

 excellent discussion of Riker (1946) on the preparation of manuscripts. 



The student should become familiar with the microscopic character- 

 istics of the fungi used in the experiments. He should make frequent 

 microscopic observations during the experiment and look for microscopic 

 changes, such as abundance and maturity of spores. Contaminants are 

 often more easily recognized under the microscope. Drawings are often 

 desirable as records of differences in microscopic characteristics. 



EXERCISE 1 

 General Laboratory Procedure 



Exercise 1 is suitably carried out by the instructor as a demonstration 

 of general laboratory techniques. This affords the instructor an oppor- 

 tunity to discuss the details of various procedures and to acquaint the 

 students with the laboratory facilities. It is convenient to prepare suffi- 

 cient stock culture medium, e.g., medium 1 (Ex. 2), for growing the 

 inoculum required by the class for the next exercise. 



General directions for preparing media. The culture medium should 

 be selected with the purpose of the experiment in mind. The precautions 

 to be observed may be elemental or elaborate, depending upon the pur- 

 pose for which the medium is to be used. The accuracy of one measure- 

 ment should be consistent with the accuracy of the others. The weights 

 of each constituent of a given lot of medium should be written in a note- 

 book. As each constituent is measured, make a check mark against this 

 constituent. 



Never weigh chemicals directly on the balance pans. Use a clean piece 

 of paper or watch glass. The weights are placed on the right-hand pan 

 as you face the balance. Be sure the spatula is cleaned between weigh- 

 ings of different chemicals. If you remove more of a chemical than 

 necessary, discard the excess. (Material still on the spatula may be 

 returned to the stock bottle.) Keep the stock bottles closed. This 

 prevents the entrance of dust and atmospheric moisture. Malt extract, 

 yeast extract, and peptone quickly absorb water from the air, and when 

 these substances have done so, an intractable mass results. 



For work of ordinary accuracy use a graduated cylinder for measuring 

 liquids. Volumetric glassware should be used for precise work. The 



