36 Journal of Agricultural Research voi. xvii. No. i 



Apparently there was little or no injury in any case. As shown by 

 the percentage of germination in the checks the killing of all seeds in 

 the case of Natal grass where 30 ounces per thousand cubic feet for 2 

 hours was used probably was due to the low vitality of the seeds. 



A number of experiments have been conducted with fungi and bac- 

 teria in which they were treated with various amounts of the formaldehyde 

 vapor and for different lengths of time. Five different organisms, Monilia 

 fructigena, Colleiotrichum gloeosporioides, Fusarium vasinfectum, Asco- 

 chyta sp., and Bacillus caratovorus were used in the following experiments. 



The spores were exposed to the treatment in four different ways: 

 (i) Three drops from a cloudy water suspension were placed on the bot- 

 tom of a sterile petri dish with a sterile platinum loop and dried before 

 treating. (2) Three drops of the suspension were placed in a dish as 

 above and the dish was placed in the treating chamber before the drops 

 had dried. (3) The drops from the suspension were placed on sterile 

 cover glasses and these were then placed in sterile petri dishes and 

 treated. After treatment the cover glasses were removed to another 

 petri dish in order to avoid a chance of getting any great amount of 

 formaldehyde into the culture medium when the plates were poured. 

 (4) Masses of dry spores were used. The masses of spores were placed 

 on cover glasses by smearing with a platinum loop containing an abund- 

 ance of spores taken from the surface of a pure culture. These cover 

 glasses were then handled as described under the third method. 



The checks were made in the same way as the plates used in the first 

 method except that they were not treated in any way. After the treat- 

 ments all plates were poured, using potato agar. They were kept under 

 observation for from a week to 10 days. 



The use of different amounts of formaldehyde solution and changes in 

 duration of the treatment show that under the conditions described 10 

 ounces of standard formaldehyde solution per i ,000 cubic feet for i hour 

 will kill the organisms used when they are exposed in a thin film. When 

 a mass of spores is used, more time is necessary to kill them. 



The masses of organisms or spores in the case of Bacillus caratovorus 

 and Monilia were killed when formaldehyde was used at the rate of 10 

 ounces per 1,000 cubic feet for 2 hours; Ascochyta spores in mass were 

 killed when formaldehyde was used at the rate of 20 ounces per 1,000 

 cubic feet for i hour; but 20 ounces per 1,000 cubic feet for 2 hours was 

 necessary to kill the masses of spores of Colletotrichum. Fusarium 

 proved to be the most resistant, and a test was made using the spores of 

 four different species of Fusarium in masses. Formaldehyde was used 

 at the rate of 30 ounces per 1,000 cubic feet for 2 hours, and in all cases 

 growth occurred. 



Following the above experiments some work was undertaken to deter- 

 mine the effect of formaldehyde vapor on the fungous spores and bacteria 

 borne on the surface of seeds. Five seeds of each of the various kinds 



