and Laboratory Methods. 1775 



thousands of mature ovules and were able to study over one hundred spermatozoids. 

 The results were, that the form of spermatozoids seen, was found to be very much 

 the same as described by Mr. Hirase, except that there is no tail. This fact was 

 announced in a short note by Mr. Fujii^ in the September number of the Botan- 

 ical Magazine, and also in a note by myself ^ in the next number, both in Japanese. 

 Mr. Fujii gave several figures of the spermatozoids in a later paper, -^ published 

 also in Japanese. 



Our observations were confirmed by Mr. Bessey, who for the first time had 

 the opportunity' of studying the living Ginkgo spermatozoids outside of Japan. 



Since Mr. Hirase's extensive paper appeared in 1898, there was nothing 

 written in English or any other European language about the spermatozoids of 

 Ginkgo, excepting a short abstract of the paper* read by Mr. Bessey at the 

 Baltimore meeting of the Society for Plant Morpholog}' and Physiolog}' in De- 

 cember, 1900. It is the object of the present paper to make a brief statement 

 of the studies on Ginkgo spermatozoids since their discovery, and to describe 

 briefly the methods of studying them. 



Ginkgo biloba, the only survivor of a once flourishing group of plants, finds 

 its native home in Japan and China, mostly in a cultivated condition. The 

 plant is a deciduous tree with beautiful fan-shaped leaves, and may sometimes 

 reach a height of over one hundred feet and be more than five feet in diameter. 

 The tree is monoecious, and pollination, in middle Japan, takes place about the 

 end of April or early, in May. Fig. 1 shows a female Ginkgo tree in the Botan- 

 ical Garden of the Tokyo Imperial Universit)-. This is the tree which furnished 

 Mr. Hirase with the material for his famous investigations, and the material for 

 our studies was also largely taken from this tree. The male plant which furnishes 

 the pollen for this tree is at a distance of about half a mile, located in a Buddist 

 temple, outside of the garden. 



The pollen from the male tree, being carried by the wind, reaches the ovule 

 of the female, and germinates inside a small cavit}', called the pollen-chamber, in 

 the vipper part of the nucellus. The mature pollen grain consists of three cells : 

 the vegetative cell, the central cell (or antheridial cell), and the tube cell (Fig. 

 2 A). The first prothallial cell formed soon degenerates, and now appears merely 

 as a cleft between the persisting second prothallial cell (Fig. 2, Az/.), the vegeta- 

 tative cell, and the outer pollen wall. After the germination of the pollen, the 

 central cell divides into two cells, — the stalk cell and the generative cell (or body 

 cell).^ The latter enlarges and finally divides into two equal cells which form the 

 spermatozoids (Figs. 2-5). It takes a little over four months from the pollination 

 to the formation of spermatozoids. 



1. Fujii, K.- — Has the spermatozoid of Ginkgo a tail or not.-" Bot. Mag. Tokyo, 12: 287- 

 290, 1898. 



2. Miyake, K. — On the spermatozoid of Ginkgo. Bot. Mag. Tokyo, 12: 333-339, 1898. 



3. Fujii, K. — On the morphology of the spermatozoid of Ginkgo biloba. Bot. Mag. 13 : 

 260-266, 1899. 



4. Bessey, E. A. — Notes on the spermatozoids of Ginkgo. Science, 13: 255, 1901. 



Dr. Webber, in his recent monograph on " Spermatogenesis and fecundation of Zamia" 

 (Bulletin No. 2, Bureau of Plant Industry, U. S. Dept. Agr. 1901) gives a somewhat careful 

 review of Mr. Fujii's two papers. 



5. Mr. Hirase describes the division of the central cell as merely a nuclear division, no 

 wall being formed between the daughter nuclei. 



