210 ARCHER, ON CYLINDROCYSTIS, 
conjugation in the different forms present a series, in their 
way, almost as varied as do the germ-cells and spermatozoids 
of other Algze—not so pronounced, it is true, but still point- 
ing, I think, to an analogy. 
It will be proper, in pursuance of the argument, to advert 
to some of the varied examples ; but, in the first place, it will 
be advisable briefly to draw attention to certain cases where 
a true fertilisation has been proved in other families, and then 
to compare that act and its results with some of the Conju- 
gate. 
In Vaucheria there exists a large globose germ-cell, and 
exceedingly minute, very numerous elongate spermatozoids, 
both elements of the fructification originating in neighbour- 
ing specially formed branches of the tubular filament, these 
not distinguishable at their first commencement from one 
another, or, indeed, from ordinary branches, though afterwards 
so highly differentiated. Here the difference m form and 
size between the germ- and sperm-cell is very great, and the 
resultant spore developes directly into a new plant. The 
difference of opinion between observers (Karsten,* Prings- 
heim,+ Dippel{) as to the modus operandi of the fertilisation 
in this genus does not seem to bear on the immediate ques- 
tion; for, whether the “ hornlets” (antheridia) actually inos- 
culate with the openings of the oogonia or not, the essential 
circumstance seems to be the union of the contents of the 
two organs. I certainly never have encountered any Vau- 
cheria in which any such inosculation of the two organs 
seemed to exist, and Pringsheim’s account appears to be the 
most trustworthy. 
Again, in Spheroplea the cell-contents of the very long 
ordinary joint of a particular filament become broken up into 
a number of rounded germ-cells ; and the contents of another 
ordinary joint become broken up into an innumerable number 
of little biciliated subfusiform spermatozoids, which latter 
find their way out of their parent-cell, and into the cavity of 
the joimt which contains the germ-cells, through lateral open- 
ings in each. ‘The fertilised oospore eventually developes 
two coats, the outer beset with spme-like extensions. Here 
the difference in size and appearance between the germ- and 
sperm-cells is less than in Vaucheria, whilst the resemblance 
of the parent-cells in which they originate is still greater, 
* Karsten, in ‘ Botanische Zeitung,’ x, p. 85 (1852). 
+ Pringsheim, in ‘ Berichte der Berl. Akademie.’ 
{ Dippel, “Ueber der Fortpflanzung der Vaucheria sessilis,” in ‘ Flora,’ 
1856, pp. 481, 497. q 
