10 TECHNICAL BULLETIN 14 9, U. S. DEPT. OF AGKICULTUKE 



Maltose Agak 



Maltose ^ grams__ 5. 00 



Magnesium sulphate do ■ 10 



Calcium nitrate do . 50 



Potassium phosphate, diliydi'ogeu do . 25 



Agar do 15. 00 



Water liter— 1 



Maltose agar, prepared according to the foregoing formula, which 

 is the standard culture medium in use in the cryptogamic laboratory 

 at Ann Arbor, Mich., was used for isolation and culture of fila- 

 mentous fungi and for isolation of yeasts. This agar remains clear 

 and light colored and may be autoclaved at 15 pounds for 20 minutes, 

 or even at higher temperatures and for longer periods, without hy- 

 drolysis sufficient to prevent solidification. 



Single germinating spores are easily located when sprays are made 

 on maltose agar, and transfers are facilitated on account of its firm- 

 ness. Most of the pathogenic filamentous fungi used in these investi- 

 gations grow well on it and produce spores abundantly. The yeasts 

 grow slowly, and for this reason it serves well for their isolation, but 

 it is unsatisfactory for culturing, and for the study of these 

 organisms. 



Leonian's Nutrient Agar 



Potassium phosphate, dihydrogen grams 1. 25 



Magnesium sulphate do . 625 



Peptone do . 625 



Maltose do 6. 250 



Malt extract do 6.250 



Agar do 13. 00 



Water liter 1 



Leonian's agar is darker and softer than maltose agar and is there- 

 fore less desirable for the isolation of single germinated spores. 

 On account of its softness, cultures do not ship well on it unless 

 partially dried. It was found to give the best results for the isola- 

 tion of filamelitous pathogenic fungi from the infected tissues of 

 bees. Hyphae from small pieces of infected tissue spread more 

 rapidly into this agar than into peptone agar ; consequently the dan- 

 ger of contamination from germinating spores of fungi other than 

 the one desired is lessened, since spores appear to germinate with 

 equal rapidity on either of these agars. Conidia of the filamentous 

 fungi form early and abundantly on Leonian's agar, and all of the 

 yeasts encountered in these investigations grew well on it. 



CzAPEK's Solution Agar 



Sodium nitrate grams— 3. 00 



Potassium phosphate do 1. 00 



Magnesium sulphate do . 50 



Potassium chloride do . 50 



Ferrous sulphate do . 01 



Sucrose do 30. 00 



Agar do 15.00 



Water liter__ 1 



All of the Aspergilli considered here and described by Thorn and 

 Church {^5) were grown by them upon this medium. It was there- 

 fore used for the culture and identification of all of the forms of 

 Aspergilli that have been found to be pathogenic to honeybees. 



