48 Mr. William Ingrams. 
microscopist, after all have been cleaned and mounted in the 
usual way. I have dealt somewhat at length on this part of 
the subject. One would have liked to have said a little more, 
but, perhaps, enough has been said to help our younger members 
to find the diatom. 
The nature of the diatom and a few particulars respecting it 
will be the next division of our subject. It has at different times, 
as observers have discovered or have fancied they have disco- 
vered, certain peculiarities, been frequently handed over, at one 
time to the animal, at another to the vegetable kingdom. It is 
scarcely worth while to go over the same ground again now. 
What remains to be said appears to be conclusive evidence that 
its proper place is the vegetable kingdom. One point, a most 
important one, is that sunlight causes it to evolve oxygen, which 
may be seen in bubbles like so many pins’ heads on a velvet 
cushion, and these may help you in your search for some of the 
more beautiful forms. The free forms have powers of motion 
which render it difficult to believe that they are not animals, but 
all are due to vital processes and the nature of the element in 
which they live. Some of these motions may be seen at 9. 
The varieties are numerous, varying in size from the seventieth 
to about the twelve hundredth part of an inch. Many, of 
these dimensions, may be seen on nearly all the slides. 
In its natural state, fixed or free, the diatom consists of two 
parts—the solid and the liquid—the cell—for such it is—and the 
cell contents. The contents are two, one coloured called endo- 
chrome ; the other, colourless. The latter is sometimes called 
the protoplasm, and by slightly touching the end of one of the 
larger forms with a fine-pointed needle, it is possible to discharge 
both. The colouring particles will diffuse themselves over a 
considerable space under the microscope, and form minute 
raised granules which infusoria tell me are very nice, and the pro- 
toplasm will form a globule having much the same consistence 
as oil. 
It is very difficult to find out what becomes of these 
contents. When confined in the cell, they assume different 
forms at different seasons, but in what must be called the final 
stage the free forms, laden with their precious freight of 
granules and globules, move hither and thither as if in quest 
of a spot suitable for their deposition. Unfortunately for the 
microscopist, in diatomaceous gatherings, too many of these 
are to be found on the surface of the drop under examination. 
They suit the diatoms nevertheless, and many may be ob- 
served relieved of their granular contents. Many an hour’s 
patient watching, at different times, will not, perhaps, be 
rewarded by a glimpse of what takes places; but by great 
good fortune, I have seen this phenomenon more than once, 
