TRANSACTIONS 
OP THE 
HERTFORDSHIRE NATURAL HISTORY SOCIETY. 
i. 
THE DIATOMACEiE ; WITH SPECIAL EEFEEENCE TO SPECIES 
FOUND IN THE NEIGHBOUEHOOD OF HEETFOED. 
By Isaac Robinson. 
Read at Hertford , ‘I'dth November , 1883. 
At some of the previous meetings of the Society I have had the 
pleasure of showing specimens of the Diatomacese under the micro¬ 
scope, and I have when doing so been frequently asked, “ What 
are Diatoms ? ” I therefore thought we might suitably devote an 
evening to the study of these minute organisms, though I fear the 
subject is one which is but little known to our members, and one 
in which consequently but little interest is felt. I hope, however, 
to he able to show that it is a subject which not only deserves 
a careful study, but which also amply repays it. I believe, also, 
that our own locality in the neighbourhood of Hertford, abounding 
as it does with rivers and streams, is particularly well adapted to 
the prosecution of such a study, and likely to yield exceptionally 
good results. Such has indeed been my own experience, and I 
think some of the facts which I shall adduce will fully bear out 
this opinion. 
Our knowledge of this branch of Natural History is, compara¬ 
tively speaking, of very recent acquisition. So minute are the 
individual forms of the Diatomacese that they are invisible to the 
naked eye, and we are therefore entirely dependent upon the micro¬ 
scope for our knowledge respecting them. If we look back to the 
time of Shakespeare, we shall find it necessary to include them 
amongst those subjects of which Hamlet says :—“ There are more 
things in Heaven and Earth, Horatio, than are dreamt of in our 
philosophy.” For many years after Shakespeare’s time diatoms 
still remained undreamt of, indeed they do not appear to have been 
I 
VOL. III.—PART I. 
