318 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



TABLE LXVI. — Shoiving Effect of Duration of Steep in Formol Sohitiotis on 

 Germinative Faculty of Seed-Corn. 



If the seed-corn so disinfected be sown on the fields the effect of 

 the treatment is visible during the first stage of germination, but after 

 thirty days there is no difference. A 0'l-0-2 per cent solution of formic 

 aldehyde, say 0-2-0-5 per cent of 40 per cent formol, may be used 

 with impunity to disinfect seed-corn. 



Action of Formol on Fungi. — -The surprising properties of 

 formol, its action on micro-organisms, were recognized and examined 

 by Trillat. He determined that its bactericidal capacity equalled 

 that of corrosive sublimate, and that its extremely diffusible vapours 

 are endowed with the same antiseptic properties. He believes that 

 its action results from its property of rendering albuminous matter 

 insoluble ; formol acting on the protoplasm of the bacteria hardens 

 it instantly, and they are thus unable to continue their evolution. 

 Bardet at;rees that formol acts in the same manner as on gelatine, 

 on the envelopes of bacteria and on the spores of fungi and renders 

 them unfit to discharge vital functions. It has, on the other hand, 

 been seen that corrosive sublimate acts in a similar manner on al- 

 buminous bodies. Numerous experiments made on different bacteria 

 by Trillat, Berlice, Miquel, Aronson, Schmitt, Stahl, Wortmann, 

 Fayollat, and others, show that a dose of 1 in 10,000 to 1 in 20,000 

 of formol generally suffices to sterilize culture media and to render 

 bacteria sterile ; it takes at least 1 in 1000 of formol to kill them. 

 Penicillium fungi and aspergillus alga) behave similarly, according 

 to the experiments of Trillat. A solution of 1 in 10,000, or the 

 ambient air containing 1 in 20,000, prevents the development of young 

 spores. These are the doses of corrosive sublimate recommended by 

 Hitchcock, Carleton, and Wuthrich as sufficient to prevent the ger- 

 mination of the spores of different parasitic fungi. The action of 

 formol on the spores of cryptogamic parasites ought, therefore, to be 

 about the same as that of corrosive sublimate. Although the remark- 

 able properties of formol were known since 1888, it was only in 1896 

 that Geuther tried to use this product in agiiculture, and after fortunate 

 results recommended it for disinfecting seed-corn in place of hot water 

 or blue vitriol. The experiments made with this end in view show 



