COMPARATIVE STUDIES ON RESPIRATION. 



II. The Effect of Anesthetics and Other Substances on the 

 Respiration of Aspergillus nicer. 



By F. G. GUSTAFSON. 

 (From the Laboratory of Plant Physiology, Harvard University, Cambridge.) 



(Received for publication, September 6, 1918.) 



The object of this investigation is to compare the action of anes- 

 thetics and some other substances on the respiration of a fungus with 

 similar effects in other groups of organisms. 



The fungus which has been used throughout these experiments is 

 Aspergillus niger. This was selected because it grows well in a nutri- 

 ent solution and forms on the surface of the liquid a compact mass 

 of hyphas, which is easily handled. Penicillium sp. was also tried, 

 but this forms loose tufts of hyphae, which are very hard to. 

 manipulate. 



The fungus was grown in a nutrient solution of 40 gm. of cane sugar, 

 2 gm. of KNO3, 1 gm. of KH2PO4, and 0.5 gm. of MgS04 in 800 cc. 

 of tap water. This solution has an acid reaction, a fact which may 

 have been beneficial in preventing the growth of bacteria. The cul- 

 tures were examined at various times for bacteria but at no time were 

 any found. The fungus was grown from spores in 100 cc. Erlen- 

 meyer flasks, in about 30 cc. of sterilized nutrient solution. They 

 were kept slightly above room temperature. Spores were usually 

 formed in 3 or 4 days after inoculation, so it was found best to use 

 the cultures when 2 days old. The respiration was at its maxi- 

 mum at this time. If older cultures were taken respiration was 

 not so great. 



The indicator method^ was used for determining the amount of 

 CO2 given off. For buffer solutions borax and boric acid solutions 

 were used in various mixtures. A table for making up buffers of 



^ Haas, A. R., Science, 1916, xliv, 105. 



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