PROGRESS OF MICROSCOPICAL SCIENCE. 
159 
silica in the form in which they employ it, have actually succeeded in 
proving beyond question the highly interesting and novel fact that 
the very minute skeletons or shells of which the infusorial earth is 
mainly composed are carried up as such into the body of the plant 
itself. Upon this point the following gleanings from an investigation 
conducted by Professor P. B. Wilson will be read with interest. 
This chemist subjected to a microscopical examination the straw 
from the wheat-fields of Colonel J. B. Kunkel, of Frederick County, 
Maryland, which had been fertilized by the silicated phosphate, his 
purpose being to make " a more complete investigation into the 
silicious structure of the stalk, in determining whether the infusoria 
passed directly as such into the sap-cells, to be carried forward by 
capillary force, and to finally assume their functions — the formation 
of the epidermal shield for giving strength to the straw, to withstand 
the destructive force of high winds and beating rains, as well as a 
protection against the attacks of parasites. 
"In making these investigations thorough precautions were ob- 
served to cleanse the straw from all accidental impurities by washing 
and gentle friction, not sufficient, however, to destroy the epidermis. 
The organic matter was 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 silicious coating was adjusted upon the field of the micro- 
scope, some thirty-six forms of the Diatomacete, 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 interlacing of these forms 
presents itself, sometimes side by side, at other times overlapping." 
From this very interesting observation Professor Wilson advances 
a number of inferences, which are of sufficient interest to warrant 
their reproduction. He affirms that his investigation "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 con- 
clusion some months since, now confirmed by that of the microscope. 
" My mind was particularly impressed with the absence of the 
disk-like form, the Actinocyclus Ehrenbergii and the Actinoptyclms un- 
dulatus 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 capil- 
laries, 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 investigation 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 
