Marks , employed for classifying the Schizomycetes. 143 
or nitrogen affect this matter ; and experiments in vacuo , or 
under pressure may give further information. 
4 . Temperature : — 
The range of temperature within which growth and other 
functions are carried on should be clearly recorded ; and the 
optimum- temperature is even more important than the maxi- 
mum and minimum cardinal points. It is best to determine 
these most in detail with the organism growing on or in the 
best nutrient medium ; and it must be remembered that the 
cardinal points are not necessarily the same for all media. 
5 . Morphology and life-history : — 
It seems advisable to defer the working out of the biological 
details until the best conditions of growth, &c. have been 
determined on pure mass-cultures. The prevailing forms of 
cells will of course be recorded, and cultures (examined from 
time to time, or, better, continuously observed under the 
microscope), must be made to determine the morphological 
changes. The shapes, sizes, mode of union, and sequence of 
division in the growth-forms ; development of zoogloeae ; 
aggregation into colonies, presence of sheaths, capsules, 
cysts, matrix, &c. ; the development of spores — endospores 
or arthrospores : motile forms, cilia ; flexibility or rigidity of 
filaments ; involution forms, & c. all come under this head. 
6. Special behaviour : — 
If spores are obtainable, the further peculiarities should 
present fewer difficulties, except in abnormal cases — which 
exist, however. The growth on gelatine should give char- 
acters of the following kind ; but it must be noted that 
these characters may vary if the conditions are varied, and 
precautions taken accordingly. Answers should be obtained 
to at least the following questions : — Does the organism 
peptonise and liquefy the gelatine ? If so, is the liquefaction 
complete? If incomplete, what is the shape and course of 
the liquefying area, funnel-shaped, tunnelled, general, &c.? 
What are the sizes, colours, and shapes — lumpy or flat, 
circular, radiately branched, &c.- — of the colonies ? 
If it only grows in fluids, are skin-like pellicles formed, or 
