38 Notes on Diatomacezx. Mou Ce 
consider them as “simple organisms,” whose morphology and life 
history, as well as classification, are therefore proportionally easy of 
comprehension. I have devoted many years to the earnest study, 
under varying conditions, of these examples of complex simplicity, 
and pity it is that others who have not spent so much time over 
this branch of organic existence should not have been so fortunate 
as I was in possessing a wise and patient counsellor in the late Dr. 
Walker-Arnott. I can truly say that had it not been for his in- 
valuable friendly advice, I too would have doubtless ranged myself 
with the manufacturers of species and synonym accumulators. 
Often have the kindly words he has written me made me pause ere 
I, as he pithily remarked, “ rushed into print” with supposed dis- 
coveries, which I would have been ashamed of thereafter. Dr. 
Arnott says, “a microscopist looks on everything as subservient to 
the microscope, and that whatever he sees, and which appears 
distinct to the eye, he thinks ought to be described or figured as 
distinct. I am, on the other hand, a naturalist, a botanist in par- 
ticular, and use the microscope, simple or compound, as a necessary 
evil, merely to enable my eyes to see better minute structures ; but 
whether these differences amount to specific or generic importance, 
or are only peculiar forms of one species, is the result of analogy, 
a mental process which can only be attained by a training in botany 
in all its branches, for many years.” Natural objects, hke the 
Diatomacex, which can only be seen after they are magnified several 
thousand times, and then only under peculiar circumstances of illu- 
mination, must be difficult of comprehension, even if their life 
history were much more simple and more easily studied than it is. 
I cannot too strongly caution the intending student of this enticing 
branch against trusting to a few and hasty observations made upon 
the dead skeleton of the plant. It is only when they are studied in 
the living state that the Diatomaceze can be understood, and even 
then only with difficulty. 
But one more abstract from my note book and I must draw 
these remarks to a close. In the early part of November, 1868, I 
made a collection of Colletonema vulgare, and for some time have 
been able to keep it alive in a bottle so as to study its peculiarities. 
And here let me say that many minute forms of both animal and 
vegetable life which I have been unable to rear otherwise, I have 
found to flourish in phials with small necks, or those with large 
ones which have the aperture partly stopped with a loose cover of 
some kind. It would seem that the gases given off from the human 
body, and accumulating in dwelling rooms, in which I have kept 
specimens, are deleterious to these small forms, and the partial closing 
of the vessel prevents, to a great extent, their entrance. My speci- 
mens of Colletonema flourished finely and grew considerably. I 
have been thus enabled to watch them, as I may say, building their 
