HISTORICAL, 
Tue bacteria are the lowest organisms, situated 
upon the limit of the two kingdoms, animal and 
vegetable, and are thus defined by the botanists 
who have most recently occupied themselves with 
them : — 
‘Cells deprived of chlorophyll, of globular, ob- 
long, or cylindrical form, sometimes sinuous and 
twisted, reproducing themselves exclusively by 
transverse division,’ living isolated or in cellular 
families, and having affinities which approach them 
to the algz and especially to the oscillatorize.” 
But, before arriving at this degree of relative 
precision, the history of the bacteria has passed 
through the most diverse vicissitudes. At one 
time considered as animals, at another taken for 
vegetables, transported from the alge to the fungi, 
one author has even gone so far as to refuse to 
them the nature of living beings.” This diversity 
of opinions is due to the minuteness of their di- 
mensions and the difficulties with which their ob- 
servation is surrounded. 
1 Reproduction by spores has been proved to occur in Bacillus subtilis, 
and it seems altogether probable that other species are reproduced in 
the same way.—G. M.S. 
2 Polotebnow. 
