XIV GLOSSARY 



Smith's (Theobald) phenomenon. The acquisition of hypersensitiveness to 

 serum and other proteid substances (normally inert) which occurs in 

 some animals as a result of minute doses of these substances, and leads 

 to rapid death, with acute symptoms, when a second injection is given. 



Specificity (species, an image). A direct relation of cause and effect between 

 two substances (such as diphtheria toxin and its antitoxin, the latter being 

 only produced by, and acting only on, the former), or between a substance 

 and a phenomenon (such as the tuberculin reaction, produced only by 

 tuberculous products in a tuberculous animal). The specific products of 

 a micro-organism are those produced only by that organism, so that their 

 recognition is proof of its presence. In the same way a specific disease 

 is one produced only by a certain bacterium (such as diphtheria or 

 anthrax), and not by several organisms (such as suppuration or actino- 

 mycosis) . 



Spermotoxin. A cytolysin to spermatozoa. 



Stimulin. A substance having the power of stimulating the action of the 

 leucocytes (more especially in regard to phagocytosis) by a direct action 

 on the leucocyte itself. The existence of these substances is doubtful, 

 most of the phenomena supposed to be caused by them being due (a) to 

 the action of opsonins, and (b) to substances which have a positive 

 chemotactic action, attracting leucocytes to the region. 



Syncytiotoxin. A cytolysin acting on the cells of the placenta. 



Thermolabile. Easily destroyed by heat. In general thermolabile substances 

 are destroyed, completely or partially, by an exposure to 55 C. for half 

 an hour or to 60 C. for 10 minutes. 



Thermostable. The opposite to thermolabile, q.v. 



Thyrotoxin. A cytolysin acting on the cells of the thyroid gland. 



Toxin (TOJ-LKOV (frapiiaKov, the drug with which poisoned arrows were anointed. 

 TO^OV, a bow). The specific poison on which the pathogenic activity of a 

 micro-organism depends. The fact of its being specific excludes simple 

 chemical substances which may also exert a toxic action. 



Toxoid. A secondary modification of a toxin which has lost its power of 

 producing toxic symptoms, but retained that of combining with antitoxin 

 or susceptible cells ; or, in Ehrlich's terminology, one that has lost its 

 toxophore, but retained its haptophore, group. > 



Toxone. A specific substance of feeble toxicity and slight affinity for anti- 

 toxin which is supposed to be produced by certain bacteria, notably that 

 of diphtheria, in which case it is believed to be the cause of paralysis. 

 Unlike toxoid, it is a primary product. Its existence is doubted, and the 

 effects attributed to minute amounts of toxin by some authors. 



Toxophore group. The portion of a molecule of toxin on which the toxic 

 activity depends, the destruction of which converts the molecule into one 

 of toxoid. 



Trichotoxin. A specific cytotoxin for ciliated epithelium. 



Vaccination. The production of active immunity by some process less 

 severe than the induction of an ordinary attack of the disease in 

 question. 



Vaccine. A substance (usually a dead culture or living culture of mitigated 

 virulence) the injection of which leads to the production of active im- 

 munity with less risk than that which accompanies an ordinary attack of 

 the disease. 



Virulence (virus, a poison). The property or properties of an organism in 

 virtue of which it is able to give rise to disease in animals or to produce 

 a powerful toxin. 



Zootoxin. A poisonous substance of animal origin which resembles in other 

 respects (and especially in that it can give rise to the production of an 

 antitoxin) the bacterial toxins e.g., snake venom, eel serum. 



Zymophore group (&M, leaven). The portion of an enzyme or enzyme-like 

 substance on which the specific properties depend, in contradistinction to 

 the combining or haptophore portion. 



