186 Transactions of the Royal Microscopical Society. 
the work some general remarks may be admissible, and to make 
these we shall have to refer to the monads severally described ; but 
as these are unnamed, and reference is therefore difficult, we will 
venture to distinguish them by the names by which for working 
purposes we designated them in our diaries. The first was the 
cercomonad, described in the tenth volume of the ‘ M. M. J.,’ at 
p. 53. The next we called the “springing” monad, from its 
peculiar habit of coiling and uncoiling one of its flagella with a 
darting motion, not unlike the vorticella, carrying the body with 
it. This is described at p. 215, ibid. The third we designate the 
“ hooked monad,” from the presence of a persistent hook-like 
flagellum, described and figured in vol. xi., p. 7. The fourth we 
call the “ unifayellate ” monad, being possessed of only one flagel- 
lum, and that at the anterior part of the body. It is described at 
p. 69, ibid. The next is the “ biflagellate or acorn monad,” being 
possessed of two anterior flagella, and at almost all stages of its 
development has the posterior end of its oval sarcode shaped like 
the cup of an acorn. This is described in vol. xii., p. 261. And 
the one we are now about to describe we name the “calycine” 
monad, from what will be seen is its peculiar calyx-like form. It 
has been before stated that the acorn-like form was the one which 
first arrested our attention ; but we were unable to study its com- 
plete development either in this or the following summer. It was 
almost the only species that existed in the maceration for nearly 
three months; scarcely anything indeed existed with it save 
Bacterium termo. But at the end of the time named it was rapidly 
superseded by the form which we are now about to describe ; and 
most of the other monads we have described appeared simulta- 
neously with it. 
At the end of the first year we had accumulated a large 
number of individual observations, the correctness of which was 
confirmed by subsequent work, but the connection, correlation, and 
interpretation of which at the time entirely baffled us. To the 
practised worker with high powers it is well known that it is very 
much more difficult to discover an obscure or delicate phenomenon 
than to see it again after once the actual discovery has been made. 
A minute striation or an exquisitely attenuated flagellum may cost 
immense labour and perseverance to find , but once found it is easy 
to see it again and again afterwards. And curious as it appears to 
us now, many of the processes with which we are now familiar 
and can easily discover, then eluded us ; so that even into the 
second year of working it would not have been at all out of 
harmony with the facts, as we then saw them, to have inferred 
that the biflagellate monad, the springing monad, the hooked 
monad, and the calycine, described below, were all connected in 
one cycle of generation, or at least in some way related to each 
