1876.] Infusorial Earth and its Uses. 345 
then removed by the prescribed methods, aided by my own 
experience.” 
“ My labours,” he continues, “ have been amply rewarded 
by one of the most enchanting views that has ever fallen to 
my lot to behold through twenty years of varied scientific 
investigations. When the epidermal siliceous coating was 
adjusted upon the field of the microscope, some thirty-six 
forms of the Diatomacese, which I have carefully sketched, 
were observed (see engraving, magnified 300 diameters) 
where perfect disintegration has been produced. When the 
structure to a great extent is retained a marvellous inter- 
lacing of these forms presents itself, sometimes side by side, 
at other times overlapping.” 
From this very interesting observation, Prof. Wilson ad- 
vances a number of inferences, which, although the writer 
is not prepared to accept in full, are of sufficient interest to 
warrant their reprodudtion. He affirms that his investiga- 
tion “ overthrows all theories that have ever been advanced, 
that silica enters into plant structure in combination with 
the alkalies, the alkaline earths, or the earths proper. 
Chemical investigation led me to this conclusion some 
months since, now confirmed by that of the microscope.” 
“ M}' mind was particularly impressed with the absence 
of the disc-like form, the Actinocyclus ehrenbergii and the 
Actinoptychus undulatus in their perfect state in the straw, 
while the other forms are common both to the infusorial 
earth and the wheat. My conclusions are that the varieties 
mentioned are too large to enter the root capillaries, for on 
the field of the microscope they have three to four times the 
magnitude of the others. This I will fully investigate during 
the coming summer, by making accurate measurements of 
rootlets and diatoms, when I will be able to obtain stalks of 
wheat as grown in the fields, preferring this mode of investi- 
gation to pot culture, to disarm controversy, and to divest the 
investigation of all semblance of laboratory experiment.” 
“ I have examined various specimens of wheat straw taken 
at random from the market, but have failed to find a single 
diatom. This to a certain extent surprised me, when taking 
into consideration that they are found to a limited extent in 
Peruvian guano. The inference to be drawn is, that the 
soil was not fertilised by any material into which it entered 
as a constituent. I mention this to guide others who may 
make subsequent investigations from falling into error, in 
case occasional Diatomaceae are observed, as being derived 
from other sources than the infusorial deposits.” 
“ These microscopic investigations show the absence of 
