MOVEMENT OF SPERMATOZOIDS. OF 
or Ginkgo, and so far as the writer has been able to learn are the largest 
that have been observed in either the animal or vegetable kingdoms. 
The cilia are also very prominent and numerous, measuring from 40 
to 50 # in length. When observed under the microscope in a living 
condition the spermatozoids are densely granular and of a yellowish 
brown color by transmitted light. By reflected light under a low 
magnification they are white and opaque. The cilia and the helicoid 
spiral band to which they are attached can be easily seen, while the 
structure of the nucleus and cytoplasm is so similar that the nucleus 
can not be discerned. 
The motion of the spermatozoids when swimming free in sugar solu- 
tion is in no way different from their motion when in the pollen tube. 
The general motion is a continuous rotation of the body, always in the 
same direction, around an axis passing through the apex of the heli- 
coid spiral. Viewed from the head end or apex of the spiral the rota- 
tion is in the direction of the hancs of a clock and contrary to the turns 
of the spiral band. They roll around, first here, then there, resem- 
bling in this respect the motion of Pandorina. After moving about 
rapidly for from five to fifteen minutes they usually cease all progres- 
sive motion, but continue to rotate for a considerably longer period. 
The rotary motion also soon ceases, but the cilia continue to vibrate 
foraconsiderably longer time. The spermatozoids of Zama also have 
an amoeboid motion, which is particularly noticeable while they are 
inclosed in the pollen tube. ‘The apex of the spiral as a whole fre- 
quently rotates in a most remarkable way, turning in a circle, pushing 
out first this way and then that way with the greatest freedom of motion, 
as if selecting a point of exit or ingress. In other cases the base or the 
side of the spermatozoid body may be considerably extended as a blunt 
point in pushing between two obstacles. The whole body seems flexi- 
ble and changeable in the highest degree and is eminently fitted for 
its difficult task of finding and swimming through the narrow passage 
between the neck cells of the archegonia. This amceboid motion is 
highly suggestive in connection with the possible motility of non- 
ciliated sexual cells in sea weeds and seed plants. It seems almost 
certain that, the spiral sperm cells that have recently been described as 
occurring in a number of seed plants— L7/7wi (Nawaschin, Guignard), 
fritilaria (Nawaschin), Triticum (Goroschankin), Silphium (Merrill), 
etc.—will be found to have such a rotating amceboid motion even if 
they are not ciliated. The writer is not aware that attention has 
before been called to this mode of motion in sperm cells. 
The vibration of the cilia in yigorous spermatozoids is exceedingly 
rapid and difficult to study. Judging from observation made on cer- 
tain spermatozoids just starting motion and others which had nearly 
exhausted their energy, there would seem to be a rhythmic contraction 
_ of the cilia which passes quickly from one end of the band to the 
