Bacteriolytic Element found in Tissues and Secretions. 3 1 5 



beeu tested and the relative amounts of lysozyme contained in these have 

 been found to be comparatively constant, except in the case of saliva, which 

 seems to vary considerably, although it never approaches in lysozyme- 

 content tears, sputum, or nasal mucus. 



The Question as to whether Lysozyine cj;ists in Tissues other than Human 



Tissues. 



Only a limited amount of work has been done in this direction, but it is 

 sufficient to show that lysozyme is very widespread in nature. Rabbit and 

 guinea-pig tissues were examined and it was found that nearly all of these 

 contained some lysozyme for the M. lysodeikticus, but in general the lysis was 

 not nearly so marked as it was with the corresponding human tissues. It may 

 be noted that the lachrymal secretion of both these animals contained no 

 lysozyme for the M. lysodeikticus, against which the human tears are so powerful. 

 The tissues of a dog were much more lytic than those of the rabbit and 

 guinea-pig, but even they were not so active as human tissues. 



It was found that egg-white was very rich in lysozyme for the M. lysodeikticus, 

 there being, after incubation for 24 hours, lysis visible to the naked eye when 

 a dilution as great as 1 in 50,000,000 was employed. Egg-white also 

 contains lytic substances for many other bacteria. It was found also that 

 commercial dried egg albumin was very rich in lysozyme. 



In the vegetable kingdom it was found that turnip had a very definite, 

 though not very strong lytic action on M. lysodeikticus. Several of the other 

 common table vegetables were tested, but they appeared to be devoid of lytic 

 activity. 



Does the Lysozyme act on Bacteria other than the M. lysodeikticus ? 



In the investigation of this problem the method adopted was to make a 

 suspension of the bacteria of such a strength that it gave a very decided 

 opacity when diluted with an equal amount of saline ; |- c.c. of this suspen- 

 sion was mixed with the same quantity of a l-in-50 sputum extract or a 

 dilution of tears from 1 in 100 to 1 in 1,000. As a control, a twofold dilution 

 of the original suspension was made with normal salt solution. The tubes 

 were incubated at 45° C. and observations were made at intervals up to 

 24 hours, the opacity of the tube containing sputum or tears being compared 

 with that of the control tube. 



Three groups of microbes were tested : the first group consisted of 104 

 strains of bacteria derived from the air of the laboratory, and of these 

 75 per cent, were dissolved, more or less readily, by a 1 in 100 dilution of sputum. 

 These air-borne bacteria consisted mainly of cocci of various sorts, but there 

 were also bacilli, yeasts, and two species of mould. 



