786 EXPERIMENT STATION RECORD. [Vol.38 



days' exposure, while in anotiier it remained infective for 51 days, although 

 putrefaction set in after a few days' exposure, and by the thirtieth day the 

 blood was completely desiccated. In two other observations blood was still 

 infective after nine days' exposure to the air, and in a third it was infective 

 after seven days' but noninfective after nine days' exposure. In two observa- 

 tions the virus maintained its vitality in bone marrow for nine days, but in one 

 cf these cases infectiveness was lost after 15 days. Meat was infective after 

 three days in one observation when blood from the same animal was noninfective 

 within that period ; in another case meat remained infective for five days. 



" Further tests are necessary to determine the factors influencing the survival 

 of the rinderpest virus in animal tissues under natural conditions. The tem- 

 perature at which the material is kept appears to have a considerable effect, 

 possibly in determining the rate and character of the putrefactive changes taking 

 place, but it has been shown that these may not destroy the virus as rapidly as 

 many authorities have stated to be the case." 



A new method for the separation of toxins, particularly tetanus toxin, 

 E. S. London and V. M. Aeistovsky (Compt. Rend. Soc. Biol. [Paris], 80 {1911), 

 No. 15. pp. 756-758; abs. in Chem. Ahs., 12 {1918), No. 1, pp. 43, 44).— The 

 method is called a method of specific coagulation by ions, and depends upon 

 the specific property of the tetanus toxin of diminishing the surface tension 

 of the colloidal particles of culture bouillon and precipitating itself on the 

 surface of those particles whose surface tension corresponds to the distension 

 of the toxin itself. By selecting an electrolytic substance whose ions are 

 capable of exercising a pressure on the surface of the particles charged with 

 the toxin, a coagulation can be formed containing the toxin. 



The method employed for tetanus toxin consists of first adding to the culture 

 bouillon ammonium sulphate in a concentration of 17 gm. per 100, centri- 

 fuging, and rejecting the precipitate. On addition to the filtrate of ammonium 

 sulphate (1 to 3 gm. per 100), the precipitate which forms contains the toxin. 

 The toxic coagulum dried in a vacuum is dissolved and reprecipitated by ammo- 

 nium sulphate of the right strength until animal tests show that further puri- 

 fication will not increase the toxicity of the preparation. 



This method should be considered only as a scheme which must be modified 

 each time, depending upon the quality of the substances used in the preparation 

 of the bouillon, the toxicity of the cultures, etc., but it is the opinion of the 

 authors that it is a method of general application in the preparation of toxins 

 and ferments. 



An antigen for use in complement fixation in tuberculosis, M. S. Fleisher 

 and G. Ives (Jour. Lab. and Clin. Med., S {1918), No. 5, pp. 302-305) .—The an- 

 tigen described is prepared as follows: 



Tubercle bacilli from a number of different strains are isolated from sputum 

 and grown on Petroff's medium for six or eight weeks. The organisms are 

 then transferred to a sterile open Petri dish, dried overnight in an incubator at 

 37° 0., transferred to a sterile mortar, and ground thoroughly for three or four 

 hours with the addition of a small amount of distilled water. Sufficient 0.S5 

 per cent sodium chlorid is then gradually added to make a 0.5 per cent sus- 

 pension of bacteria, the grinding being continued until the bacteria form an 

 even suspension. Finally enough of 5 per cent carbolic acid is added to equal 

 one-tenth the volume of the sodium chlorid solution. 



The antigen is considered to be a suspension and a watery extract of tubercle 

 bacilli, both of which have the power of fixing complement in the presence of 

 the sera of tuberculous individuals. The entire antigen is stronger than either 

 the fluid or the suspended matter alone. From results obtained with the 



