94 FECUNDATION ; HETEROGAMETES. 
VAUCHERIA. 
With the possible exception of SAheroplea annulina var. braunte, 
we have dealt thus far with heterogamous fecundation in those alge 
with uninucleate cells. We shall now examine the sexual process in 
three notable types, one from among the algz and two from the fungi, 
namely, Vaucheria, Albugo (Cystopus), and Achlya, in which the 
cells are multinucleate. 
In the species under consideration, Vaucheria clavata, both anthe- 
ridia and odégonia may be considered as short side branches cut off 
from the parent filament by transverse septa. The primordium of the 
antheridium (Oltmann’s, ’95) contains numerous small nuclei which 
probably multiply by division. After the formation of the transverse 
wall, the nuclei become spindle-shaped, move into the central vacuole, 
and assume a radial arrangement. Each spindle-shaped body sur- 
rounded by a court of fine cytoplasm free from chlorophyll represents 
a spermatozoid. Very fine threads visible in the antheridium were 
regarded as cilia. 
Concerning the réle of the nuclei during the development of the 
odgonium, the several authors differ somewhat. According to Schmitz 
(79) the numerous nuclei present in the young oégonium probably 
fuse later into one. Similar results were obtained by Behrens (’90). 
Schmitz (’83) claimed that, in the plasmic mass extruded on the 
opening of the oogonium, smal] nuclear fragments were present, 
which had probably become separated from the nuclei of the young 
oogonium. Klebahn (’92) disputed the above conclusions and asserted 
that, long after fecundation, he had observed numerous nuclei in each 
odspore. Oltmanns (’95), using®more exact methods, found that a 
union of the several nuclei in the young oogonium does not take place, 
but, on the contrary, all save one pass back into the parent filament 
before the formation of the transverse wall cutting off the odgonium. 
The development of the oogonium, according to Oltmanns, is as 
follows: Together with the protoplasmic mass numerous nuclei pass 
into the primordium of the oogonium (Oogonanlage) (Fig. 34, A). 
The nuclei, which are in the neighborhood of the future beak, prob- 
ably undergo division, thereby increasing their number. As soon as 
the oogonium has reached its definite size, a retreating movement of 
the plasmic mass sets in, and a portion of the plasma, with numerous 
chloroplasts and nuclei, re-enters the mother-filament (Fig. 34, B). 
The single nucleus remaining tarries awhile in the beak at the bound- 
ary between the colorless and chlorophyll-bearing plasma, but finally 
