PROCESS OF FECUNDATION. 63 
moving spermatozoids of Ginkgo, but he has fortunately been able to 
observe and study some of those obtained by Mr. Bessey, and can con- 
firm the main features of the movement as described by him. The 
tail-like appendage which was described by Hirase certainly does not 
exist in the normal spermatozoids, and in the specimens observed by 
Hirase was doubtless due to compression in escaping from the pollen 
tube or some similar cause, as suggested by Fujii. The shape of the 
spermatozoids which have been observed by Mr. Bessey and the writer 
corresponds well with those figured by Hirase and Fujii. The move- 
ments of the spermatozoids of Ginkgo are almost exactly the same as 
those observed by the writer in Zamia. The amceboid movement of 
the apex of the spiral is very noticeable in Ginkgo also, and the ryth- 
mic motion of the cilia, similar to that occurring in Zama, has been 
observed by Mr. Bessey. 
A very interesting observation, first made by Mr. Bessey and also 
studied by the writer, is the rythmic vibration of a portion of the 
membrane at the base of the spermatozoid corresponding with the 
vibration of the cilia. The spot is apparently just over the ‘‘ corps 
spherique,” and may have some relation to that body. 
PROCESS OF FECUNDATION. 
While the spermatozoids have been maturing, the proximal ends of 
the pollen tubes, as described above, have been growing down through 
the tissue of the nucellus into the archegonial chamber above the arch- 
egonia. When all of the organs are developed ready for fecundation 
the pollen tubes hang down so that the ends almost or quite touch the 
neck cells of the archegonia, which protude into the same cavity. It 
is interesting to note that the pollen tubes when they enter the arche- 
gonial chamber (endosperm or prothallial cavity), which seems to be 
filled simply with moist air, do not grow at random, but bend slightly 
outward and grow directly toward the neck cells of the archegonia. 
Frequently several were observed to grow toward the same archego- 
nium. These observations can be made on living material by carefully 
cutting into the archegonial chamber at one side, without injuring the 
tubes, and observing them witha hand.lens. The end of the tube is 
occupied by the spermatozoids and the vegetative cells of the male 
prothallus. It is probable that the spermatozoids normally begin 
swimming in the tubes before the latter burst, as they have several 
times been observed swimming in the unbroken tubes. The end of 
the pollen tube is wider than the upper portion and is evidently under 
considerable tension. The protruding tip formed by the old pollen 
grain (figs. 47 and 51) is plainly visible with a hand lens, and is evi- 
dently the point which first comes in contact with the neck cells of the 
archegonium. The neck cells are also distended and turgid and are 
evidently easily broken. If in this distended condition the end of 
