GLOSSARY 303 



Mutations sudden variations appearing in individuals of one 



species and capable of transmission to their descendants. 

 Mycetozoa or Myxomycetes protozoa with naked protoplasm 



occurring on damp surfaces in the form of jelly-like masses, 



living on organic debris, arncebiform without mycelium but 



later plant-like. 

 Myeloplax a multinucleated cell occurring in the marrow of 



bones. 

 Nematodes a class of worms with thread-like body, mouth and 



intestinal canal, including the parasitic thread-worms, &c. 

 Neuroglia cells in the nervous system which correspond to the 



connective tissue cells in other organs. 

 Nitrification the transformation of salts of ammonia (chiefly the 



sulphate and the carbonate) into nitrites and nitrates under the 



influence of the nitrifying bacteria. 

 Plasma the fluid portion of the blood freed from the red and 



white corpuscles which float in it : it contains fibrinogen but, 



not having been allowed to coagulate, no fibrin (vide Fibrin). 

 Proteins substances resembling egg-white and containing nitrogen, 



carbon, oxygen, hydrogen, and sulphur. 

 Ptomaines products of putrefaction, some of them poisonous, 



isolated from putrefying organic matter (first discovered in 



dead bodies). 

 Putrefaction the decomposition of protein substances by microbes 



and their ferments with the production of gas, foul smells, and 



sometimes poisonous substances : as a result of putrefaction 



organic matter is restored to the state of inorganic elements. 

 Septic derived from o-7r<m corruption and applied to material 



which can produce or undergo bacterial infection, e.g., a septic 



wound, a septic instrument, a septic dressing. Hence the 



words " antiseptic," a substance acting against this action, and 



"aseptic," the absence of sepsis. In modern surgery antisepsis 



has given place to asepsis. 

 Serum the clear fluid expressed from the clot of coagulated blood : 



it represents the fluid portion of the blood minus the cells and 



minus the fibrin which forms the clot (vide Fibrin). 

 Stereochemical the chemistry of matter may be treated as 



depending on arrangements of the atom in space in the 



molecule (vide isomeric). 

 Sucrase sugar-splitting ferment. 

 Symbiosis the living together of dissimilar organisms each 



dependent on the other : the best examples are the lichens 



where a fungus and an algae live together. 

 Urease urea-splitting ferment : producing ammonia from the 



urea, the main nitrogenous constituent of urine. 

 Vagus the nerve supplying the heart, lungs, and stomach. 

 Vitalism the modern application is to a theory which postulates, 



at least provisionally, some other activity in the life processes 



