234 
Rickett.—Fertilization in Sphaerocarpos . 
Penetration of the Antherozoid into the Egg. 
If one observes a male culture under a binocular microscope, many 
involucres may be seen to extrude from their tips small globules of whitish 
sticky material. These globules may be picked off with a needle or fine 
brush and deposited in a drop of water on a slide, or the whole plant may 
be transferred to the drop for a short time. The drop of water, upon 
examination with a high power of the microscope, proves to contain numerous 
antherozoids, which after a few minutes disentangle themselves from the 
surrounding viscous material and begin to swim around in the water. 
If killed and stained in the manner already described, their form is that 
shown in Text-fig. i. 
Text-fig. i. Antherozoids shortly after having emerged from the antheridium. x 1300. 
An antherozoid consists of a slender rod, variously curved or coiled, 
bearing two cilia attached near the anterior end, and a cytoplasmic vesicle at 
the posterior end. This vesicle is, apparently, soon lost. The cilia are not 
attached at the same point. At the anterior end of the body of the anthero¬ 
zoid is a less deeply staining portion. One cilium is attached at the 
anterior end of this body, the other just posterior to it. Measurements 
of the cilia of the antherozoids figured show a difference in length between 
the two cilia of each individual ; the anterior cilium measuring quite 
constantly 44 /x, the posterior one from 46-5 to 50 • 5 yu. ; an average differ¬ 
ence of 3-6 /x. The average length of the body of the antherozoids figured 
is 18 /x, the individuals varying from 16 to 20 /x. The body is 0-5 /x thick. 
Of all stages in fertilization the actual entrance of the antherozoid into 
the egg is the most difficult to observe. The neck at this time is filled with 
the mucilaginous material described above, and the space in the venter 
above the egg with the remains of the ventral canal cell; all of which forms 
