SUGAR IN THE NUTRIENT MEDIUM. 137 



succeed in securing a sufficient growth of these organ- 

 isms upon a non-albuminous medium. Brieger and 

 Colin found that cholera vibriones formed a non- 

 albuminous virus upon the Uschinsky nutrient me- 

 dium. The diphtheria virus is also recognized now 

 as free from' albumin (Brieger and Boer: L c.). 



It is becoming more and more customary to call 

 the bacterial poisons simply toxins and to ignore 

 entirely the existence of the above-described crystal- 

 lizable toxins of simple constitution. 



Concerning the other characteristics of these tox- 

 ins I will make a few remarks, taking the tetanus 

 virus as an illustration (Brieger and Cohn: L c.). 

 Watery solutions are not coagulated by heat but lose 

 their poisonous properties in time. The addition of 

 small amounts of acid or alkali to produce solution, 

 and prolonged transmission of carbonic acid and 

 sulphuretted hydrogen impair the toxicity very ma- 

 terially. In the dry state the virus tolerates a tem- 

 perature of 70 very well for a long time, higher 

 temperatures decompose it rapidly. When dried 

 and protected from light, air, and moisture, it is 

 converted slowly into an inert substance. It is bet- 

 ter preserved when covered with absolute alcohol, 

 anhydrous ether, and the like. 



The virulence of the purest tetanus virus is almost 

 inconceivable. A mouse weighing 15 gm. is killed 

 by 0.00005 mgm. ; a man weighing 70 kgm., with the 

 same susceptibility, would be killed by 0.23 mgm. 

 Thirty to one hundred milligrams of strychnine are 

 required to kill a man. 



