— ee Le 
DR. HICKS, ON FRESH-WATER ALGAE, ETC. 7 
upon which I ask, What about the rest? How can they be 
considered really distinct, unless you now go over the whole, 
and prove them one or the other? I do not absolutely deny 
their separate existence, but I do say here is enough evidence 
to set us to work again to study the life-history of each; and 
certainly, till each one is again worked out, we cannot (not- 
withstanding all our affection for our old acquaintances) con- 
sider any one as finally placed. 
But Mr. Archer relies most (talking of Palmoglea Brebis- 
sonii) upon the fact of conjugation as the most certain test 
of the fixity of species, believing it as the analogue of 
pollen-impregnation, and therefore as showing the maturity of 
the cells in which it occurs ; any cell therefore conjugating he 
looks upon as the perfect form of it. We must doubtless admit 
that this process is one of considerable character, and an 
important phase of the life of the cell; and also that, traced 
downwards, there is something in the analogy to favour this 
conclusion which is shared by many. Yet I may ask, 
without going into the whole question, looking at the process 
itself, have we any direct evidence that it is anything more 
than a direct fusion of the contents of two cells? Whilst 
admitting the value of the analogy, ought we to ascribe more 
value to the act than really appears? What, for instance, is 
it in Spirogyra? A process of one cell joins with the process 
of another, and their contents thus being able to come into 
contact, fuse into one mass. Before the change began it was 
impossible to perceive any difference between the two cells. 
Further than this, we often find in some species that should 
no second filament be near enough, the two adjoining cells 
of the same filament conjugate by throwing out processes 
round the jomt which divides them, and then their contents 
fuse. In Palmoglea Brebissonii not the slightest difference 
can be perceived between the two cells. Mr. Archer admits 
this, though in some few he has noticed a difference between 
the conjugating cells, as if an approximation was being made 
to the antheridal cell. Still, upon the whole, they are both 
apparently similar. Therefore setting aside analogy, but 
stating the case as we actually observe it, we cannot but call 
it an act of simple fusion of the contents of two cells. Are 
we justified in our present state of knowledge in placing so 
much importance upon it as to make it a test of the most 
perfect condition of the cell? 'To do so at present would be 
arguing somewhat in a circle. For our safe advancement it 
seems to me best not so to use it, but merely to note the fact 
and the mode in which it occurs, reserving its use as a test 
when we have advanced further in knowledge. Some day 
