154 BACTERIA. 



of the organisms in question. Be'champ terms microbes microzyma, 

 or small ferments, since the chemical reactions which result from 

 their vital activity are generally ferments. Bacteria are distin- 

 guished from animal cells by being able to derive their nitrogen 

 from ammonia compounds, and they differ from the higher 

 vegetable cells in being unable to split up carbonic acid into its 

 elements, owing to the absence of chlorophyll. 



The Schizomycetes^ or " splitting-fungi^' — German, SpaltpilzC' — 

 ((TKi^co — I splits i-ivKOi^ungus) are tmicellular plaiits^ 7vhich multiply 

 by repeated subdivisions in one, two, or three diniensiofis of space, 

 a?id also frequently reproduce themselves by spores, ivhich are formed 

 eiidogenously. They live, either isolated or combined in various 

 ways, ifi fluids and in livijig or dead organisms, i?i which they 

 produce decompositions and fermentations, but never alcoholic fer- 

 mentation. 



I shall use here the method I gave in my paper on Amoibce in 

 the American Monthly Microscopical Journal for July, 1889, which 

 may be altered to suit requirements : — {a) Structure, {J)) digestion, 

 {c) absorption, {d) circulation, {e) respiration, (/) secretion, 

 (o-) nervous system, {h) sense-organs, (/) motor organs, {k) repro- 

 duction, (/) development, {in) classification. 



Practical Work. 



Every plant or animal must be seen, examined, dissected, 

 and drawn. 



{a) Structure, 



I. — Occurrence. Wherever there is putrefaction they are 

 present in vast numbers : in water, in soil, in sewage, in the 

 intestines, and in uncleanly persons — especially on the skin and 

 between the teeth — various species may be found. The red 

 colour noticed in mouldy bread is due to Bacteria. Such diseases 

 as diphtheria, typhus fever, consumption, cholera, anthrax (or 

 " wool-sorters' disease "), appear to depend on their presence. 



Many cases of fermentation are due to the presence of these 

 organisms, and the putrefaction of plants and animals seems to 

 result from fermentations originated by them. Students who may 

 wish to prepare these organisms without the help of disease will 



