BACTERIA IN THE INDUSTRIES. Ill 



were sent to the farmers with instructions how to scatter them through an 

 infested corn-field. The results were in some instances very satisfactory, 

 and again without appreciable effects. The trouble in the use ofjhis exter- 

 minator lay in the fact that the climatic conditions (rainy, damp weather) 

 essential to the spreading of the disease did not generally prevail, and as 

 soon as the climatic conditions were favorable inoculation became unneces- 

 sary, as the disease developed without artificial aid and effectually checked 

 further ravages. 



Rabbits are one of the very annoying field pests of Australia, and at- 

 tempts have been made to exterminate them by means of pure cultures of 

 microbes capable of developing a fatal infectious disease among these 

 animals, but the results were quite unsatisfactory. 



More recently there have been placed on the market quite an array of 

 mice and rat exterminators of microbic origin under various trade names 

 as ratin, rat virus, azoa, rattite, Danysz virus and mouratus. These prep- 

 arations consist of pure cultures of bacilli pathogenic to rats and mice, as 

 the Bacillus murisepticus and Bacillus ty'phimurium, mixed with some inert 

 base, as corn-meal, oat-meal, etc., forming a coarse powder. Some prep- 

 arations are in liquid form. They are used by mixing the powder or liquid 

 with moist corn-meal or other food material relished by these animals, and 

 spreading it near their haunts and runs. Fortunately, these substances are 

 harmless to man and animals other than mice and rats. These microbic 

 rat and mice exterminators have thus far proven to be rather unsatisfactory. 

 They have undoubtedly given excellent results in some instances, and again 

 they have been absolute failures. The tests made by the University of 

 California, and by Dr. Rupert Blue in his famous plague-rat extermination 

 in San Francisco, have given almost wholly negative results. A microbic 

 squirrel exterminator ("squirrelin") has proven entirely unsatisfactory. 



When we consider how difficult it is to prevent fatal epidemics, it cer- 

 tainly does seem reasonable to suppose that it should be a comparatively easy 

 matter to find ways and means for disseminating fatal epidemics, but so far 

 the commercial attempts made in that direction have proven rather discourag- 

 ing. Further carefully conducted experiments along this line are necessary. 

 It is known ' that the ravages of certain pests are sometimes suddenly 

 checked by the natural invasion of some pathogenic organisms. This is fre- 

 quently observed among plant lice (Aphis) and other insect enemies of plants. 



5. Bacteria in the Tanning Industry. 



The object in tanning leather is to protect it against decomposition and 

 to render it pliable. The various animal hides before reaching the tannery 

 are preserved by drying and salting. At the tannery the hides are treated 

 as follows: 



