54 BIOLOGY OF PNEUMOCOCCUS 



extractions, when added to pneumococci at pH 5.5 to 6.95, dis- 

 solve the cells, but no action takes place if the reaction is as acid 

 as pH 4.5. From this observation Lord and Nye concluded: "An 

 enzyme derived from the bacteria themselves or from the cellular 

 material may be the cause of the dissolution." Avery and Cullen 38 " 41 

 supported this hypothesis. Autolysates and sterile solutions of 

 pneumococci, when added to suspensions of pneumococcal cells in 

 phosphate solutions of known pH previously heated to 60° for 

 thirty minutes, or 120° for twenty minutes, caused lysis of dead 

 pneumococci and, to a less extent, disintegration of closely allied 

 organisms such as S. viridans, but they had no effect on Staphylo- 

 coccus aureus. The enzyme was most active in a substrate with a 

 reaction between pH 6 and pH 8 ; it was destroyed by heating for 

 thirty minutes at 60° and was not type-specific in its action. The 

 bacteriolytic action was proportional to the concentration of en- 

 zyme. Avery and Cullen expressed doubt whether lysis of pneumo- 

 cocci under these circumstances was the result of a single enzyme 

 or the product of the interaction of more than one. The matter was 

 left undecided by their saying that "whether the enzyme or group 

 of enzymes concerned in autolysis of pneumococci play any part 

 in this form of lysis are questions at present undecided." 

 In 1929, Goebel and Avery 520 were able to state that: 



1) Autolysis of Pneumococcus is accompanied by proteolysis, which 

 results in an increase in amino and non-coagulable nitrogen; 2) autoly- 

 sis of Pneumococcus is accompanied by lipolysis during which there 

 is a liberation of ether-soluble fatty acids; 3) when extracts containing 

 the active intracellular enzymes are added to heat-killed pneumococci, 

 lysis of the cell occurs and there is an increase in the non-coagulable 

 and amino nitrogens, comparable to the changes accompanying spon- 

 taneous autolysis; 4) when extracts containing the active intracellular 

 enzymes are added to emulsions of the alcohol-soluble lipoids extracted 

 from pneumococci an increase in the ether-soluble fatty acid occurs. 



In spite of the earlier belief of Jobling and Strouse (1913) 680 

 that lysis of pneumococci may be independent of ferment action 

 and the statement of Pauli 1071 that this autolysis is due to the self- 



