70 A MANUAL OF THE PENICILLIA 



the following composition: 



Yeast extract 2.0 grams 



Peptone 3.0 grams 



Dextrose 2.0 grams 



Sucrose 30.0 grams 



Corn steep solids 5.0 grams 



NaNOs 2.0 grams 



K2HP04-3H20 1.0 grams 



MgS04 0.5 grams 



KCl 0.2 grams 



FeS04-7H20 0.01 grams 



Distilled water 1000 ml. 



Agar 20.0 grams 



Adjust before autoclaving to pH 7.0 



Preparation of Cultures 



Recognizing the necessity of laboratory cultivation, and assuming the 

 availability of suitable media and cultui-e facilities, the preparation of 

 different types of cultures which are important in the study of the Peni- 

 cillia will next be considered. 



Two types of culture vessels, namely test tubes and petri dishes, should 

 be constantly available in adequate numbers. Of these, the first is of 

 particular importance for the maintenance and storage of stocks, whereas 

 the latter is invaluable for the detailed observations of colonies and coni- 

 dial structures upon which successful diagnosis depends. Tubes of an}^ 

 convenient size may be employed. In our work we have found tubes 

 measuring 15 x 125 mm. to afford adequate space for limited culture de- 

 velopment, and at the same time to conserve valuable storage space. 

 Standard petri dishes, 10 cm. in diameter by 1.5 cm. deep, are used for 

 most purposes. A larger dish, measuring 15 cm. by 2 cm., is very useful 

 for dilution plates and for other types of cultures in which many colonies 

 are to develop, or in which the worker wishes to observe individual colonies 

 over an extended period. 



TYPES OF cultures 



Test Tube Cultures 



The preparation of test tube cultures is practically essential in the han- 

 dling of a Penicillium. Inoculation of such tubes is usually made by wire 

 or loop from a selected mass of mycelium or spores. In studying speci- 

 mens as received, or as newly isolated, transfers to test tubes should be 

 made before any other studies are begun. This will perpetuate as nearly 

 as possible the exact content of the original culture or specimen. Reculti- 

 vation may ultimately show the original to be valueless, in which case the 



