EXPERIMENT STATION BULLETINS 337 



be possible perhaps to arrive at a more satisfactory conclusion than by thinking 

 of germs in the abstract and as invisible objects. Should the growth of a vigorous 

 plant be watched and the obstacles with which it has to contend be noted during 

 its progress, its strong powers of resistance would be very prominent. On the 

 other hand, should the plant be weak and lacking in the power to push ahead, the 

 obstacles which had little influence over the strong plant would become fatal 

 enemies to the weak. In bacterial life there are the strong and the weak germs. 

 While a germicide may act with great rapidity in the case of the weak, it may not 

 be able to cope with the strong. Especially is this true when the two forms of 

 the same germ are considered. The vegetative form and the spore form are as 

 distinct in their relations to germicides as it is possible for two different species to 

 be. The vegetative form is the germ before the spore has germin.itcd within it, 

 and yields quite readily to the action of germicides. After the spore has formed, 

 germicides act with great difficulty because of the strong resistance offered by 

 the spore wall. In anthrax these two forms of a germ are found. The vegetative 

 form succumbs easily, while the spore form has been known to exist for years sub- 

 ject to agents fatal to the vegetative form. This explains why it is undesirable 

 to open an animal dying of anthrax, for in the body of the animal before it is ex- 

 posed to the oxygen of the air, the germs are in the vegetative form and are more 

 easily killed; but upon coming in contact with the air, the vegetative forms are 

 converted into the spore forms, which are exceedingly resistant. 



There are other difficulties to be met, not from the standpoint of the germ but 

 from the standpoint of the investigator who tries patiently to establish he true 

 value of germicides, disinfectants and antiseptics. These difficulties are largely 

 technical and are known only to the laboratory man who has devoted some at- 

 tention to this work. 



Simply a mention of the above difficulties will suffice to present what obstacles 

 stand in the way of an exact determination of agents whose characters have been 

 described above. In reviewing the agents used as germicides, disinfectants and 

 antiseptics, only those which are of practical utility to the farmer will be mentioned. 

 Those which are very good but too expensive for general application will be omitted 

 in this consideration. 



HEAT. 



This agent will be found one of the most useful of germicides or disinfectants, 

 for whenever it is possible to apply the flame direct, as a cleansing agent, or in the 

 destruction of contaminated material; whenever a dry heat may be used to ad- 

 vantage in destroying a virus upon instruments, dishes or metallic substances, and 

 whenever steam heat or boiling water may be employed for rags, clothes or any 

 fabrics which will not be injured by such usage— dishes, knives, forks, in fact, any- 

 thing that will stand steaming or boiling— this agent, heat, becomes applicable in 

 one form or another. 



The direct flame is very useful in consuming contaminated material about the 

 farm, in burning the carcasses of animals dying of contagious diseases, in destroy- 

 ing rags and old clothes which have come in contact in any way with 

 contagion, and in short, consuming anything that has a tendency to scatter 

 the disease, such as ithe discharges from the nostrils, the mouth and the bowels. 

 Whenever material containing the germ of a contagious disease is burned, all 

 danger has disappeared. All thoughts about dogs digging up carcasses and the 

 possibility of an Incomplete disinfection of any material that may be handled 

 afterward are removed and the assurance that the utmost has been done to eradicate 

 the disease gives great relief to tlie conscience. 



Hot air is usful in a great many instances when instruments or metallic sub- 

 stances, glass ware and crockery are to be disinfected and when it is undesirable 

 to apply steam heat or hot water, and the direct flame is out of the question. It 

 cannot "be recommended very highly for the disinfection of clothes, rags or any- 

 thing of a textile nature. 



Steam heat and boiling water are perhaps the most common and useful dis- 

 infectants that we have, for they can be used for pails, cloths, dishes, which have 

 been employed by patients sutt'ering from infectious diseases, bedding, clothes, 

 curtains, carpets, instruments, anything that will not be affected by the action of 

 steam or hot water. 



Heat is the most efficient disinfectant we have and should always be borne in 

 mind when any disinfection is to take place, because of its cheapness and its ex- 

 tensive application. It also acts more quickly and is more certain of destroying 

 virus than any other agent that can be named. 

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