626 Wolfe: — Cytological Studies on Nemalion. 
does not appear to be confined to such divisions alone, being seen in 
connexion with what appeared to be a much larger number of chromo- 
somes. 
The events above described constitute, in the opinion of the writer, 
conclusive evidence in support of a view long maintained, according to 
which the cystocarp of the red Algae is held to be the homologue of the 
sporophyte in higher plants. Resulting from a sexual act, intervening 
between that sexual act and the formation of spores, bearing a spore which 
gives rise to an individual unlike that upon which it is borne, and finally 
presenting double the number of chromosomes seen in the vegetative phase, 
it possesses the essential characters of such a sporophyte. 
Summary. 
Since it has seemed to the writer that the present condition of our 
information concerning the phenomena of reduction in Thallophytes is 
far too meagre and conflicting to render any further discussion of the 
subject at the present time of value, he has chosen to content himself 
with the presentation of such matters of fact as appear to have been 
developed in the course of this investigation. It may, however, be 
pointed out that in the Florideae, a family usually regarded as an 
independent and terminal phylum, or at least in Nemalion , which is not 
considered as an illustration of their highest development, a condition 
of alternation is present which, in so far as the cytological phenomena 
accompanying it are concerned, is very closely comparable with that 
which is familiar in the archegoniate series — the double number of 
chromosomes appearing after the union of the gametes and continuing- 
in the sporophyte to the point at which spore-mother-cells are formed. 
Regarding, then, the present paper as a contribution which may be of 
value when a sufficient body of information concerning such cytological 
conditions in the lower plants renders their co-ordination possible, the 
general results obtained may be summarized as follows : — 
(1) The chromatophore of Nemalion is in the form of a hollow 
ellipsoid from which processes radiate to the periphery of the cell, and 
there flatten out to form a clathrate membrane. 
(2) The region surrounded by the ellipsoid portion of the chromato- 
phore, and generally regarded as a pyrenoid, consists entirely of vacuolar 
material, and hence cannot be considered as constituting any such definite 
organ of the cell. 
(3) The chromatophore is present in all cells of the plant, with the 
exception of the mature antheridium and the two sperm-cells to which 
it gives rise ; and in all cases originates from a pre-existing body of the 
same nature. 
(4) The sex-organs cannot be regarded as unicellular structures : since 
