6 WITTROCK, SPORES OF THE MESOCARPEZ. 
effected here in the Mesocarpee principally through the mov- 
ing of the chlorophyll-coloured parts of the protoplasm (=the 
chlorophyllaceous bodies) into and to the neighbourhood of 
the somewhat widened conjugation-canal. This second and 
more important stage of the fecundation PRINGSHEIM calls 
connubium. The conjugation having taken place in this 
manner, its effect appears, as has been said before, by the 
tripartition or quinquepartition of the cruciated or H-shaped 
cell formed by the copulation. Of the cells formed by this 
partition the central one is fertile, the 2 or 4 lateral ones 
sterile. The result of the conjugation is, consequently, not 
one cell but several cells, and not cells of one kind but of 
two, namely, one propagative cell (a spore), and around it 2 
or 4 cells not capable of germination. It would be difficult 
to find a reasonable interpretation of such a result, save the 
one suggested by PRINGSHEIM, ofits being a sporocarpium. 
And to me this interpretation seems not only reasonable, 
but perfectly natural. For, although the sporocarpium does 
here remain on a very low, not to say the very lowest stage 
of development, it does however already possess the consti- 
tuent parts of a typical sporocarpium. It has a nucleus and 
a pericarpium, or at least an zxquivalent to one. The nu- 
cleus is the single, central spore-cell, and the pericarpium is 
represented by the 2 or 4 iateral sterile cells. 
A sporocarpium of so simple a construction does not 
occur in other alge, as far as is now known”). Among the 
fungi, however, a sporocarpium of an analogous construction, 
and formed nearly in the same manner, occurs in the family 
of the Piptocephalide Bref.”). 
If the explanation given above of the result of the fecun- 
dation in the Mesocarpew is accepted, the essential difference 
between these alge and their nearest relations, Zygnemew and 
Desmidiece, might be expressed in the following manner. 'The 
result of the connubium in the former is a sporocarpium 
(and their spore is consequently a carpospore), but the result 
in the latter is a zygospore”). 
!) If not in Sirogonium sticticum (E. B.) Kätz. Compare DE BARY |. c., Pp. 
14, 15, pl. 2, fig. 1—6; and PRINGSH. 1. c. p. 20. 
2) Compare O. BREFELD, Botanische Untersuchungen iiber Schimmelpilze. 
JAETefE: MöT2STFeIS and von 9: 
3) This is the case also with the genus Sirogoniwm, which differs otherwise 
as to its system of fructification not a little from the other Zygnemece. 
