THE BACTERIACE. 167 
division and by spores. Sexual reproduction has not been ob- 
served ; but as it is known to take place in the higher fungi, so also 
is it possible that in these lower forms, which in some instances 
contain reproductive corpuscles or spores, conjugation of sexual 
elements may occur, and their sexual difference being molecular 
rather than morphological may have escaped observation. The 
female is at present the only sex known, if these organisms can be 
said to possess that quality. The cells formed by transverse divi- 
sion in some cases separate from each other, and in others remain 
attached in filaments. Spores appear in some, and when the 
parent cells burst the spores are liberated ; they then begin to 
grow in one direction, assume the form of the parent, and have 
spores of their own. Sometimes in a filament of cells, each cell 
will contain only one spore; a single cell may in other cases con- 
tain several spores. Some forms are stationary, others have the 
power of motion. In some the motion is produced by flagella, 
which have been observed at their extremities. In others filaments 
of one or more cells assume a spiral form, and move either by 
rotation on their axes, aided in some cases by flagella, or they 
progress by a lateral movement of the body in rhythmical undula- 
tions. Sachs follows Cohn in dividing these organisms into the 
following four groups :— 
1. Spheerobacteria: very small round cells which separate, 
forming gelatinous masses on dead organic bodies ; often coloured. 
2. Bacteria proper: very minute motile cells, rod-like, which 
impart a milky appearance to putrefying albuminous fluids. 
3. Filobacteria: slender cells which remain united in filaments ; 
the latter either straight, as in Bacil/us, or curved, as in Vibrio. 
4. Spirobacteria: forming spiral filaments, often much larger 
than the last, as in Spzrt//um. 
This distinction between the Protophytes which contain chloro- 
phyll and those which are devoid of it, although scientifically correct, 
is not universally accepted, since not only has that substance been 
discovered in some of the so-called Bacteriacez, but some of the 
supposed Algze have been found destitute of it ; showing that if these 
organisms are allied to the Fungi on the one hand, they have also 
some affinities with the Algze on the other, and especially with the 
family Oscillatorieze, the members of which they somewhat resemble 
in their motions. ‘According to Van Tieghem, the chlorophyll of 
the two families is not identical, that of the Oscillatoriez being 
mixed with phycocyanin, whilst that of the Bacteriacez is normal. 
Seeing that the life-histories of these organisms have not yet 
been satisfactorily traced to any great extent, any classification of 
them in genera must necessarily be only provisional. The follow- 
ing is one suggested by Dr. Luerssen in 1880, which I copy from 
the Journal of the Royal Microscopical Society of that year :— 
