1923] 



DUGGAR & KARRER 



203 



that the infective particles do not withstand complete dehydra- 

 tion. 



A study of the effects of longer exposure to various grades of 

 alcohol has been carried out at some length by Allard ('16a), 

 who found that relatively speaking the infective properties are 

 quickly destroyed by the higher strengths of ethyl alcohol. He 

 indicates destruction by 80 per cent alcohol in 30 minutes. On 

 the other hand, in later work, he (Allard, '18) has shown some 

 striking resistance of the infective agency to the weaker grades 

 of alcohol. We may note a few instances. Kept in 25 per cent 

 alcohol 34 days and then inoculated into the host, 7 out of 10 

 plants developed mosaic; this, however, is obviously exceptional, 

 since in another test the virus kept in 25 per cent alcohol 199 days 

 yielded 7 out of 10 diseased plants; in 50 per cent alcohol after 

 40 days no disease was induced; in 50 per cent alcohol after 35 

 days 4 out of 10 plants became diseased. With another sample 

 of the virus in 50 per cent alcohol for about 5 days only 2 plants 

 were diseased after inoculation from this material. 



From a comparison with active cells in the vegetative condition 



be seen that these results indicate a high de 



bacterial cell may be injured after 24 hours by 



alcohol. Moreov 



hich shows a specifi 



tion, is itself injuriously affected by more than about 15 per cent 

 alcohol. If the comparison is made with the tolerance of the 

 spores of certain species of bacteria, we shall find that the infective 

 particles of mosaic are less resistant. Feeling that it was unwise 

 to accept some of the data which have been published on this 

 point, we made a study of the tolerance of the spores and vegeta- 

 tive cells of the hay bacillus, Bacillus subtilis. 



In the duplication of this work the senior author was assisted 

 by Dr. H. R. Rosen. One cubic centimeter of a dense infusion 

 of this organism was placed in a series of alcohols diluted with 

 a decoction of tobacco juice so as to get respectively 10, 20, 30, 40, 

 and 50 per cent alcohol, and similar concentrations of acetone. 

 At intervals up to 10 days, streak cultures from these concentra- 

 tions of the disinfectant yielded in each case continuous growth 

 of the organism. Similar cultures were made with a young 



