36 NOTES ON MICRO-ORGANISMS. 
found in the coal measures, so that the two classes of Saprophytes 
were co-existent so far as this epoch is concerned. 
Now, taking into consideration the three classes of Bacteria, 
moulds, and alcoholic ferments, the relation between the last two 
is so strong that I think one is quite justified in considering the 
alcoholic ferments as derivatives of the moulds, for the following 
reason :—Two or three well-known moulds can be converted 
into alcoholic ferments. This is notably the case with Mucor 
racemosus, and in the last few years Brefeld has published the 
information that he has converted a great many moulds into 
simple cells, having the ferment form 
Secondly, it appears to me that the relationship of Bacteria to 
moulds is much stronger than to alcoholic ferments, more 
especially turning on this point that the Saccharomycetes never 
show a motile state caused by Cilia. Whilst many moulds 
produce actively moving bodies or Zoospores, with Bacteria the 
motile stage is an ordinary feature. All three classes of organisms 
may form spores, but the Saccharomycetes only do so under very 
exceptional conditions, probably never as a normal method of 
reproduction. 
Bacteria in a moving state seem to display something akin to 
intelligence. The susceptibility to light has been already noted, 
and it may be mentioned besides that some organisms display a cer- 
tain ability for avoiding collisions with moving or stationary matters 
that they may encounter in their wanderings through a liquid. 
Bacteria require, as a rule, more complex forms of nourishment 
than moulds or Saccharomycetes. These last will thrive fairly 
well in a mineral solution, in which the carbon and nitrogen are 
represented by ammonium tartrate, whilst Bacteria grow but very 
feebly in the same. 
Bacteria, then, may be ranked higher than moulds or alcoholic 
ferments, for although they show characteristics which, at each end 
of the scale, join them to separate kingdoms, making it a question 
between animal and vegetable life, the weight of evidence goes, I 
should say, to point out a much nearer alliance to the former than 
to the latter condition of existence. 
