816 



SCIENCE. 



[N. S. Vol. XVI. No. 412. 



portant factors determining the issue of 

 the contest are the qualities, the relative 

 proportions and the distribution of the 

 bacterial and the host's cytotoxins. 



The hypothesis thus outlined can be 

 tested experimentallj', but I regret that it 

 has shaped itself in my mind so recently 

 that I have not yet been able to make the 

 desired experiments, -which are, however, 

 now started in my laboratory. Since my 

 arrival here I am informed that these ex- 

 periments have already furnished facts in 

 its support, which will be published later. 



Inasmuch as at least one component, and 

 it may be both components, of the assumed 

 bacterial cytotoxins preexist in the bac- 

 terial cells, it should be possible to demon- 

 strate some of them in artificial cultures 

 of bacteria, where they would be found 

 especially as integral parts of the cells, 

 unless extracted from the bodies of degen- 

 erating or dead bacteria. This corre- 

 sponds with what is known concerning the 

 situation of the poisons of the cholera spir- 

 ilhun, the typhoid bacillus and other bac- 

 teria characterized by the lack of strong 

 soluble toxins. But the quantitative and 

 other relations between these cultural cyto- 

 toxins and those prodiiced in the manner 

 described by the same bacteria during pro- 

 cesses of infection are comparable to those 

 between the normal antibodies and the im- 

 mune antibodies. These relations would 

 explain the familiar fact that cultures of 

 bacteria of the class under consideration 

 constitute in general only a partial and 

 meager index of the toxic capacities of the 

 same bacteria in the infected body. That 

 cytolysins may, however, be present nor- 

 mally in large amount is illustrated by the 

 hsemolysins of eel's serum and of snake 

 venom. 



In this theory, degenerated and dead 

 bacteria, while recognized as a source of 

 poisoning in infections, are not assigned an 

 exclusive role in this regard. Living bac- 



teria in the infected body, where they are 

 under nutritive conditions not paralleled 

 in artificial cultures, actively produce and 

 secrete receptors which may become the 

 means of intoxication of the body cells. 

 From what has been said, we can compre- 

 hend how these diverse free receptors may 

 enter into the formation of cytotoxins of 

 the most varied and specific characters, 

 such as erythrotoxius, leukotoxins, neuro- 

 toxins, nephrotoxins, spermotoxins, hepato- 

 toxins, etc. Verj^ ' probably in many in- 

 stances these toxins are represented by so 

 few receptors in bacterial cells in ordi- 

 nary cultures that it would be hopeless to 

 search for them there, although we may 

 have convincing experimental and patho- 

 logical evidence that within the animal 

 body the same bacteria produce them 

 abundantly under the stimulus of appro- 

 priate substances derived from cells of the 

 host. 



WiLLLVM H. Welch. 

 Johns Hopkins Uni^'eksitt. 



[To be concluded.) 



THE LEXGTE OF THE COLLEGE YEAR AA^D 

 COURSE* 



A NUMBER of matters of general aca- 

 demic interest have occupied the attention 

 of the imiversity faculty, and to some 

 extent that of the other faculties, during 

 the year. The established policy of grant- 

 ing no honorary degrees was unanimously 

 reaffirmed. The administration of the 

 disciplinary authority of the university 

 was devolved upon a committee consisting 

 of the dean and four professors to be 

 elected by the university faculty. The 

 better conduct of examinations was much 

 discussed; but owing to the difficultj- ex- 

 perienced in discovering the sentiment of 

 the students towards the so-called honor 



* From the tenth annual report of President 

 Sehurman to the board of trustees of Cornell 

 University. 



