854 



SCIENCE. 



[N. S. Vol. XVI. No. 413. 



the filtrates or the killed bacteria of 

 our cultures are required for the detec- 

 tion of the subtler and more specific cel- 

 lular poisons. Instances are rapidly in- 

 creasing in which by improved methods 

 cultures of bacterial species once believed 

 to be practically devoid of toxicity are 

 found after all not to be so poor in toxins, 

 even of the soluble variety. - One of the 

 earliest and most instructive illustrations 

 of this is the discovery by Van De Velde 

 of a leucocyte-destroying poison, named 

 leucocidin, in exudates caused by infection 

 with Staphylococcus aureus, and also in 

 filtrates of staphylococcus cultures, which 

 had been previously regarded as almost en- 

 tirely free of toxic power. 



More widely distributed in cultures of 

 different species of bacteria are the hsemo- 

 lysins, of which the first example, discov- 

 ered in 1898 by Ehrlich in cultures of the 

 tetanus bacillus, was carefully studied by 

 Madsen the following year, and which have 

 since been investigated by Kraus with 

 Clairmont and with Ludwig, Bulloch and 

 Hunter, Neisser and Weehsberg, Todd, 

 Besredka and others. The list of bacterial 

 species known to produce in cultures sub- 

 stances of this nature capable of dissolving 

 red blood corpuscles is already a long one, 

 and includes the bacilli of tetanus, of green 

 pus, of typhoid fever, of acute dysentery, 

 of diphtheria, of plague, the pyogenic 

 staphylococci and streptococci, the pneumo- 

 coccus, and many other bacteria. Nuttall 

 and I noted in our first descriptions of Ba- 

 cillus aerogenes capsulatus over ten years 

 ago its capacity of laking blood, so that I 

 was not surprised to find recently that a 

 hemolysin can be demonstrated in cultures 

 of this organism. The blood-destroying 

 property appears to stand in no definite 

 relation to virulence, nor is it limited to 

 pathogenic bacteria. It pertains also to 

 many putrefactive bacteria. The strongest 

 bacterial haamolysin hitherto observed was 



found by Todd in cultures of Bacillus 

 megatherium, which is a widely distributed 

 saprophyte. 



As already stated, none of these bodies 

 has been shown to belong to the class of 

 complex hsemolysins in blood, which have 

 been far more exhaustively investigated 

 than any other of the specific antibodies. 

 Doubtless there is at present among bac- 

 teriologists too great a tendency to attribute 

 to the less carefully studied antibodies char- 

 acters which have been worked out in detail 

 only for the hsemolysins of immune serum. 

 It would lead too far to attempt here a 

 discussion of the special characters of the 

 various bacterial hemolysins, which present 

 in different specimens curious and at pres- 

 ent unexplained divergences as regards re- 

 sistance to heat and several other prop- 

 erties. It must suffice to indicate briefly 

 what is known of the pathological impor- 

 tance of this interesting gi-oup of bacterial 

 toxins. 



In view of the abundant clinical and 

 pathological evidence of extensive destruc- 

 tion of red corpuscles in the course of 

 many infectious diseases, it is certainly 

 significant to find that many bacteria are 

 endowed with a specific hsemolytic power. 

 The question is how far we are justified in 

 applying to the actual conditions of infec- 

 tion the existing experimental data upon 

 this subject. Assuredly here, as every- 

 where, results of test-tube experiments, 

 helpful in suggestion as they may be, 

 should not be utilized without further evi- 

 dence to explain morbid phenomena within 

 the infected human or animal body. "While 

 much more work upon this subject is needed 

 before our information will be exact or 

 complete, the observations and experiments 

 of Besredka,* Kraus and Ludwig, f and 



* Besredka, Annales de I' Institut Pasteur, 1901, 

 XV., p. 880. 



t Kraus and Ludwig, Wien. Tclin. Woch., 1902, 

 p. 382. 



