INFECTION AND INFECTIOUS AGENTS 43 



factor, the smooth type contained an arlditional factor not pos- 

 sessed by the rough variant. 



Bordet and Gengou were working A\ith a pure culture of B. 

 pertussis. They succeeded in getting it to grow on plain agar and 

 compared the gro^vth and antigenic properties of the organisms 

 grown upon plain and blood agar respectively. The following 

 quotation from Bordet definitely bears out the above conclusions :* 

 "It [Bacillus pertussis] develops readily in the medium that is 

 rich in defibrinated blood, as already described by Gengou and my- 

 self in our first article on whooping cough. It may be taught to 

 grow on ordinary agar, in which instance it gives a thick and rather 

 coherent layer. The two varieties of organisms obtained in this 

 manner, although coming from a single original colony, give rise 

 on immunizing animals to tAvo different sera. We may consider 

 the scrum of a rabbit that has been imnumized against an organism 

 grown on ordinary agar. It is found that the serum agglutinates 

 these organisms energetically, but has no clumping effect on a 

 culture of whooping cough bacillus grown on the otlier medium 

 containing defibrinated blood. On the other liand, if we test the 

 serum of a rabbit that has been immunized against the organism 

 grown on blood media, we find that it agglutinates both races of 

 bacteria. A careful study of this phenomenon brings out the fact 

 that two definite agglutinins affecting different antigens are present 

 in different proportions. One of these antigens which is present 

 in large amounts in the organism which has developed on blood 

 is not to be found in the organism grown on agar. ' ' 



Relation of Environment to Size. — In conclusion it would 

 seem advisable to mention a few controversial theories that are 

 being investigated at the present time. It is held by Gotschlich 

 (1927), Kendall (1931), Almquist, Holmes, Enderlein, IMellon and 

 others that filterable forms of bacteria are demonstrable and that 

 these may give rise to the larger forms. Many of these claims have 

 not been confirmed. A brief but excellent review of the subject is 

 given by Zinsser and Bayne- Jones (1939). 



Entirely aside from the question of filtrable forms of bacteria 

 is the effect of the host's tissues upon the size and perhaps mor- 

 phology of certain organisms. Goodpasture (1937) finds within the 

 walls of the intestinal tract of ty])hoid ])atients coming to autopsy 



♦Reprinted by permission from Shtdies in Innnuniti/ by Bordet and Gay, 

 published by John "Wiley and Sons, Inc. 



