12 



" active interference with the growth phenomena of the organisms." 

 They also found that immune serum reduced the output of amino 

 nitrogen in cultures after 24 hours incubation and that it interfered 

 with the capacity of the coccus to ferment inulin. They sug- 

 gested that integrity of the digestive zone at the surface of the 

 bacterial cell was necessary for growth, that the action of anti- 

 enzymotic bodies was to interfere with this zone, and that capsule 

 formation was possibly an attempt to protect the function of the 

 digestive zone. 



Blake,* however, whilst admitting that specific serum appar- 

 ently caused some inhibition of the metabolic activities of 

 pneumococci, thought that this was merely due to agglutination 

 and that there was no evidence of a specific antienzymotic property 

 of the serum. Whenexhausted of its agglutinin content, the serum 

 possessed no inhibitory properties, and these properties were 

 found to be in direct proportion to agglutinating power. In 

 estimating growth by plating methods, it was obvious that, when 

 the cocci grew in clumps and chains, a sample would give fewer 

 colonies than the controls. Agglutination made the cocci unable 

 to grow in intimate contact with the whole medium ; but, when 

 the cultures were frequently shaken, the metabolic activities 

 were the same in homologous serum as in the controls. 



Barber t applied his " single cell method " to the study of 

 the problem ; he picked out, under the microscope, single pairs 

 of pneumococci and observed what happened to them when 

 they were introduced into fluids which were supposed to be 

 " antiblastic." He found that growth of a single pair in immune 

 horse serum proceeded as fast as in the controls, though the 

 character of the growth was distinctly different. " The cells 

 " early became invested with a thick capsule and grew in chains 

 • wliich often intertwined and formed zooglea-like masses . . . 

 " The capsule formed also on cells which were isolated from old 

 " cultures and were apparently dead or, at all events, subsequently 

 " showed no growth in hanging drops." He also made cultures in 

 test-tubes which were inoculated with one or two pairs and 

 subsequently counted to determine the number of generations 

 which had formed in a given time; he found that there was 

 practically no difference between growth in homologous and 

 heterologous serum, in spite of the formation of chimps in the 

 former. These results were not altered when complement was 

 added to the homologous serum. 



Attn- taking a sample of blood from a rabbit, he inoculated 

 the animal intravenously with 5 c.c. of Type I serum and took 

 a second sample of blood an hour later. The rate of growth in 

 blood, and also in serum, was the same in the two samples. 

 Again, experiments with the whole blood, serum and plasma 

 of the rabbit three days after receiving the immune serum showed 



* Journ. Expo. Med., XXVI. p. 563. 1917. 



t Journ. Bzper. Med., XXX, p. 569 and p, 580. liil't. 



