82 EXPERIMENT STATION RECORD. [Vol.40 



In tests of the effect of temperature of circulating brine on the yield of ice 

 cream it was found that a temperature of about 6° F. for the circulating brine 

 is the most desirable when using a 20 per cent raw cream. For pasteurized 

 cream a temperature of from 8 to 10° gave the best results, while for emulsified 

 cream about 10° and for homogenized cream 14° proved the most satisfactory. 

 The amount of mix in the freezer influenced the yield obtained. The most 

 satisfactory results were obtained from a horizontal freezer when it was about 

 half full of mix. 



It is stated that the daily overrun should be figured by volume, but as a 

 check the overrun should occasionally be determined by weight. The holding of 

 ice cream was found not to influence the distribution of fat in the cream. With 

 ice at $3 and salt at $7 per ton, the cost of salt and ice used Cor freezing in 

 these tests was 0.58 ct. per gallon of ice cream frozen to 27° and 0.75 ct. for that 

 frozen to 26°. For packing the cost was 1.44 cts. per gallon for 5-gal. containers. 

 It is suggested that in factories where ice and salt are used for freezing pur- 

 poses the waste brine should be collected in a cooling tank and used to cool the 

 milk and cream handled. 



VETERINARY MEDICINE. 



Tolerance and immunity, J. L. Mabchand (-four. Lab. ami Clin. Med.. 3 

 {1910), No. 10, pp. 571-601, figs. 2; abs. in Vet. Rev., 8 {1918), No. ■',. pp. .',S1, 

 482). — This la a general discussion of the subject, with clinical cases cited. 



A study of the mechanism of the agglutination and absorption of agglu- 

 tinin reaction, together with an examination of the efficacy of these tests for 

 identifying specimens of the meningococcus isolated from 354 cases of 

 cerebrospinal fever. W. J. Tut.loch {Jour. Hi/;/. [Cambridge], n {1918), Vo. 

 2-8, pp. S16-3/ f 9). — This is a theoretical discussion of the problem of aggluti- 

 nation from the standpoint of Bordet that in the process three Beparate sys- 

 tems react with one another, the antigen, the antibody, and the menstruum in 

 which these are suspended, and that the reaction is divisible into two phases, 

 the union of antigen with antibody and the flocculatlon of the antibody-anti- 

 gen complex. 



The points discussed under the first phase are (1) the influence of the re- 

 action of the menstruum in which the reagents are suspended: If the reaction 

 be too acid or too alkaline, union of antigen with antibody is inhibited, and, 

 no complex being formed, the system is aot susceptible to the flocculating 

 action of electrolytes. (2) Influence of the electrolytes of the menstruum: Evi- 

 dence that formation of the "antibody-antigen couple" is conditioned by the 

 presence of dissolved salts in the menstruum, and that results obtained depend 

 largely upon the nature of the electrolytes in the fluids employed for suspend- 

 ing the reagents. (3) Influence of the presumably inactive constituents of 

 the antigen and antibody colloids upon the process of sensitization: It is con- 

 sidered that presumably inactive substances may be present in such quantity or 

 in such a physical state that they protect the united antibody-antigen complex 

 from flocculation. (4) Quantitative relationship between antigen and antibody 

 in the process of agglutination: The relationship is considered to obey the same 

 laws as those governing the phenomenon of adsorption or surface condensation. 

 (5) Analogies between the union of antibody with antigen and certain experi- 

 ments of colloidal chemistry: The complexity of the reaction is pointed out and 

 the consequent necessity of observing special care in carrying out agglutination 

 tests. (6) Influence of the physical state Of the reacting systems upon the union 

 of antibody with antigen: If either of the reaction colloids be denatured by heat 

 prior to being mixed, agglutination may not take place. It is considered that 



