FUCACES, 85 
in a capsule of seawater until it became turbid owing to their number. If on 
examination the antherozoids proved to be active, small quantities were added 
to the vessel containing the odspheres. ('96, p. 480.) 
When vigorous antherozoids (1. c., '98, p. 631) are transferred to vessels con- 
taining healthy odspheres they at once congregate around them, and attaching 
themselves to the periphery of the eggs, cause the well-known movements by 
lashing the water with the free cilium., But, as Thuret noticed, fertilization can 
often be effected without any whirling movement taking place, and we have 
observed perfectly normal germination to follow on the addition of apparently 
inactive antherozoids to the odspheres. 
There seems to be a marked difference between the degree of attrac- 
tion exerted on the antherozoids by the egg-cells under different condi- 
tions. Thus, when the extruded products have been long exposed to 
a moist atmosphere, so that all the membranes have become deli- 
quescent, the spermatozoids are hardly influenced by the odspheres. 
On the other hand the odspheres which still retain their walls become 
covered with spermatozoids. 
The behavior of the spermatozoids in the genus Hadddrys is of 
especial interest in this connection, and I quote again from the same 
authors (I. c., ’98, p. 633): 
On watching the behavior of the antherozoids when swimming amongst the 
oospheres, they are seen to attach themselves to the surface of the eggs by one 
cilium, whilst they maintain a circular or gyratory movement around their 
point of attachment. Most often there is a number—a dozen or more—of 
these groups, each consisting of 4 to 12 antherozoids, distributed over the sur- 
face of each odsphere. The movement is always in the clockwise direction, 
and the chromatophore is on the end of the antherozoid remote from the egg. 
The rate of gyration is fairly rapid, 40 to 50 complete turns being made in a 
minute. After-this has been going on for a while the egg itself evinces 
a change, swelling somewhat and appearing more transparent than before. 
Sometimes movements of vacuoles may be discerned, and even the position of 
the nucleus may change. These alterations ensue as the definite result of the 
stimulus in some way given by the antherozoids themselves. . . . Sud- 
denly the antherozoids are seen to leave the egg like.a crowd of startled birds, 
or else they become quiescent, and these phenomena are immediately followed 
by a great change in the egg itself, which becomes warty and covered with 
conical projections. From each papilla a fine thread projects, consisting of a 
moniliform series of droplets, and the antherozoids may sometimes be observed 
attached to these threads. After the lapse of a few (3 to 5) minutes the egg 
resumes its spherical form whilst at the same time its diameter becomes 
smaller. Still later the fine threads also disappear, whilst the egg regains its 
original size. As long as the antherozoids are in active motion on the surface 
of the egg, the latter exhibits a scarcely perceptible rocking movement and is 
free in the water, but during the events which have just been narrated it 
