16 SOME FUNGOUS DISEASES OF ECONOMIC IMPORTANCE. 



DISCUSSION OF THE FUNGUS. 



Both in cultures and in the diseased fruit the fungus Thielaviopsis 

 paradoxa, studied in the Office of Pathological Collections and In- 

 spection Work, adhered very closely to its characteristic morphology. 

 In addition to the two kinds of spores, microspores and macrospores, 

 a pycnidial stage was observed which appeared irregularly and with- 

 out any unusual physical conditions, such as lack of moisture or 

 reduction in the amount of media, being apparent. 



"When the fungus was found on sound fruit in association with 

 insect remains or other foreign matter it exhibited morphological 

 differences. In small particles of such extraneous substances as just 

 mentioned, isolated fungous spores were found which resembled the 

 macrospores of Thielaviopsis, but differed in possessing a more cir- 

 cular outline, denser cell contents, and a thicker wall. In these exam- 

 inations no microspores were observed. In five days cultures made 

 from the macrospores developed normal, remarkably pure cultures 

 of Thielaviopsis. This phase is not only of interest in relation to 

 the ecology of the fungus, but it has an important significance in the 

 probable value of formaldehyde for pineapple disinfection. 



HISTORICAL REVIEW OF FORMALDEHYDE AS A DISINFECTANT 



AND FUNGICIDE. 



The important role of formaldehyde as a disinfectant and fungi- 

 cide has been demonstrated within a comparatively recent date. 

 Among the early workers who recognized its value were Guether, 

 Xeger, & Tubeuf, c Kinzel/ 2 and others. In 1898 Xeger experimented 

 with spores of Ustilago hordei, using formalin pastils to generate 

 the gas. The treatment was found to be effective in its fungicidal 

 action, and the degree to which it retarded germination was not 

 serious. Kinzel's work was concerned with the effect of formalin on 

 the germination of certain grains and legumes and its value in the 

 treatment of smuts. 



In 1906 McClintic, 6 of the United States Public Health and Marine- 

 Hospital Service, published the results of his work on formaldehyde 



a Guether, Tli. Ueber die Einwirkung von Formaldehydlosungen auf Ge- 

 treidebrancL Bericbte der Pharraaceutischen Gesellschaft, vol. 5, uo. 12, 1895. 

 pp. 325-330. 



b Neger, F. W. Ueber Desinfektion von Saatgut inittels Forinaldehyd-Dainpfe. 

 Fraktiscbe Blatter ftir Pflanzenbau imd Pflanzenscbutz, vol. 1, no. 11. Novem- 

 ber. 1S98, pp. 84-85. 



c Tubeuf. Carl von. Scberings Fornialingas-Methode. Praktiscbe Blatter 

 fiir Pflanzenbau und Pflanzenscbutz. vol. 1, no. 11. November, 1898. pp. 85-86. 



d Kinzel. W. Ueber die Einwirkung des Formaldehyds auf die Keiinkraft. 

 Die Landwirtbscbaftlicben Versucbsstationen, vol. 49, 1898, pp. 461^66. 



e McClintic, T. B. Tbe Limitations of Formaldehyde Gas as a Disinfectant. 

 Bulletin 27, Hygienic Laboratory. April 9, 1906. 

 171 



