212 ACTION OF ANTISEPTICS 



that many of those substances which affect cells, and either render 

 them inert or permanently destroy them, have in greater con- 

 centration a similar action upon enzymes. Thus alcohol, chloro- 

 form, salicylic acid, carbolic acid, thymol, and sodium fluoride, 

 which were at one time regarded as affecting living cells only and 

 without action upon enzymes, have now been shown by various 

 observers to more or less retard the action of enzymes also, and 

 to destroy them in greater concentration, although the action 

 varies in degree in different instances and is always less than that 

 upon the cell. The greater degree of action of such substances 

 upon cells has been often taken advantage of as an experimental 

 aid in observing the nature and products of reactions of enzymes, 

 especially of those proteoclastic enzymes which act in an alkaline 

 medium. For such substances stop the growth of the putrefactive 

 bacteria at a concentration in which they have little action upon 

 enzymes. This experimental use of antiseptic agents was first 

 made by Kiihne in studying the products of action of trypsin. In 

 choosing such an antiseptic, one ought to be selected which possesses 

 a strong action upon cells, but as little as possible upon enzymes, 

 and one which is now often used for the purpose on this account 

 is toluol. Another substance said to be almost without action 

 on enzymes, but most toxic for cells, is hydrocyanic acid; it stops, 

 however, the property of acting upon hydrogen peroxide which 

 is common to nearly all enzymes. Such substances as antiseptics 

 and anaesthetics produce their effects by combination with protein 

 or protoplasm; and since all enzymes and cells must be allied in 

 consisting of colloids related in character to protein, it is evident 

 that an ideal substance which will affect the cell and not the enzyme 

 is an impossibility. As a result, we have no hard-and-fast criterion 

 as to whether a given effect is produced by an enzyme or a living 

 cell, except where living cells can be ruled out by microscopic 

 examination. For, while active cells are thrown out of activity 

 by protoplasmic poisons much more readily than enzymes, there 

 exists, bridging over the interval, the sporing form of the cell, which 

 shows the same resistance to the chemical reagents that we have 

 already seen in the case of changes in temperature. 



The only true test is that of being able to grow and produce 

 the cell in pure culture, and then obtain with it the previously 

 observed chemical or biological effect. Unfortunately, this in 

 many instances fails, notably in the case of many of the commonest 



