466 Slowe, Stodola, Hayashi, and Brian 



work on this phase of the problem, and by the following year he had 

 published in Japanese his now classical paper, "Experimental studies 

 on the secretion of Fusarium heterosporum on rice-plants" (5). Kuro- 

 sawa showed that sterile filtrates from the bakanae fungus gave marked 

 growth stimulation in lice and grass. In this paper appeared the first 

 photograph found in the literature which illustrated the stimulatory 

 effect of the fungus secretion. 



It is to Kurosawa, then, that we are indebted for opening up this 

 fertile gibberellin field. I felt that a pioneer such as this deserves to 

 be better known than he is. Kurosawa was born in 1894 in the town 

 of Itabashi in Ibaraki Prefecture, and he died in 1953 at the age 

 of 59. After considerable effort Dr. Hayashi was able to find the in- 

 formal picture shown on the facing page. There you see the man 

 responsible for the work that we are so much interested in. 



The publication of Kurosawa's paper at once stimulated other 

 workers to take up the problem, of course, and in 1928 papers by 

 Hemmi and Seto appeared from the Phytopathology Laboratory of 

 Kyoto University (4, 8). In 1932 Shimada at Hokkaido University in 

 northern Japan published the first paper on the chemical nature of 

 the growth promoting principle (9). It was at this time that the 

 University of Tokyo workers became interested in the problem. 



Dr. Hayashi: In 1930 Dr. Yabuta, formerly professor of Agricul- 

 tuial Chemistry of Tokyo University, Dr. Kannbe and I studied the 

 isolation of the growth stimulating substance. In 1934, contrary to 

 what we expectetl at first, we obtained a growth deterring substance, 

 fusaric acid, that is, 5-n-butylpicolinic acid, by extracting the cultmed 

 solution either with benzene or petroleum ether. It is reported that 

 in some cases rice plants infected with bakanae organism show re- 

 duced growth instead of the usual elongation. Judging from this 

 fact, fusaric acid might be responsible for the symptoms of retarded 

 growth. In 1934 Kurosawa changed his position to Tokyo and, with 

 his help, Dr. Yabuta and I again began isolation of the growth stimu- 

 lating substance. Kurosawa furnished us with a fungus -whidi pro- 

 duced the active substance abundanlly and indicated suitable ( uliural 

 conditions. 



The isolation of the active substance from the culture filtrate was 

 carried out as follows: The fungus was grown in a medium contain- 

 ing ammonium chloride, monopotassium phosphate, and glycerol 

 by the culture method in (lask. After about one month, the culture 

 solution was filtered and the filtrate was treated \\iih activated car- 

 bon. The carbon was then eluted with methanolic ammonia. The 

 eluate was concentrated in vacuo. The resulting residue was dissolved 

 in aqueous sodium bicarbonate solution and extracted Aviili ether to 



