Marks, employed for classifying the Schizomycetes . 135 
should be stated, is only suggested as a possible way out of a 
well-known and much felt difficulty, namely, the very natural 
one that obtrudes itself on the non-botanical bacteriologists, 
who meet with numerous forms of Schizomycetes in their 
records, of rapidly identifying these forms and learning whether 
the same have been met with before. I am scarcely concerned 
here with the question whether such knowledge is worth any- 
thing or nothing: personally, I feel that all conscientious 
comparative records are valuable, however much we may 
deplore the fact that these forms are usually merely recorded, 
and not studied further. 
The first character employed by Miquel is that of aerobism. 
Now it is in some cases extremely difficult to determine 
whether a Schizomycete is aerobian or not, but of course the 
question is more easily answered if the organisms are always 
cultivated on or in the same medium. There is evidence to 
show, however, that an organism may be anaerobian in 
saccharine solutions, but aerobian on gelatine, whence diffi- 
culties may arise to those who neglect such facts. 
Miquel’s second character is the temperature. This is a 
relatively easy point to make out in some cases, but it 
presents undoubted difficulties where the optimum-tempera- 
ture lies close to the demarcation point (20° C.) selected, and 
it is by no means clear how we are to get over these diffi- 
culties. In any case the character ceases to be useful where 
the optimum-temperature is 18-22° C. 
Miquel’s third diagnostic character is the form of the 
organism. Obviously this is subject to all the criticism that 
has been accorded to the morphological systems referred to ; 
but I may now point out a truth which is frequently over- 
looked by those who criticise too severely the attempts of 
the systematists, namely, that if we have two aerobian Schi- 
zomycetes, capable of growth at the same temperature on the 
same medium, then if one of them persists in developing as a 
Micrococcus and the other as a Bacillus, we are justified in 
regarding them as distinct species. True, the converse does 
not follow, if both grow as Micrococci or as Bacilli they may 
