338 Methods of Testing 



extending to hundreds of c.c., and have frequently found their animals 

 stood the operation badly, whereas most of the animals treated in these 

 experiments continued to gain weight, and appeared to be healthy. 



In the preceding table the methods of production, animals treated, 

 their weight before and after treatment, the number of injections, and 

 the quantities used in each case, together with the power of the resulting 

 antisera are given. 



Methods nf Testing. 



In the Qualitative Experiments the method which has already been 

 fully described (p. 62 et seq.) was followed. 



Throughout the subsequent tables the following signs have been 

 used to denote the degree of clouding, and quantity of precipitum after 

 24 hours. 



+ = very marked cloud full reaction. D = very large deposit after 21 hours. 



+ = marked cloud. D = large ,, 



x =medium cloud. d = small ,, ,, ,, 



* - small cloud. tr = trace of a deposit. 



? =very slight, or doubtful, clouding. =110 reaction. 



The very marked cloud, followed by a very large deposit, was seldom 

 obtained except on the addition of an antiserum to its homologous blood 

 dilution. In a few instances closely allied sera also produced this con- 

 dition. Marked cloudings followed by large deposits as indicated by the 

 second signs occurred on the addition of antisera to nearly related bloods. 

 In some cases the antisera only gave this amount of reaction with their 

 homologous sera. Medium clouds occurred under the same conditions. 

 Powerful antisera, however, occasionally produced reactions of this degree 

 with distantly related sera. Small cloudings indicated in the tables by 

 the sign * were usually obtained when antisera reacted with distantly 

 related bloods. Such cloudings were occasionally followed by small 

 deposits (d), or traces of deposits (tr), but not infrequently after the 

 lapse of 24 hours no precipitum was found. 



The sign * ? indicates that there was a haze at the line of junction 

 of the serum and antiserum. In most cases this result was probably due 

 to some cause other than a reaction between the serum and antiserum, 

 but where an antiserum produces several such reactions on the sera of 

 a group of animals a remote relationship is probably indicated. For 

 this reason in the following tables summarizing the results of the tests 

 with the various antisera, these very small reactions have been inserted, 



