62 SPERMATOGENESIS AND FECUNDATION OF, ZAMIA. 
appearance of some such an organ on the posterior end of the sperma- 
tozoid after it has entered the archegonium. In passing through the 
very narrow entrance canal between the neck cells, the spermatozoids 
have use for all possible elasticity, as they must from necessity stretch 
out into a very long, slender form in making the passage. The act of 
passage has not been observed in Zama, but the spermatozoids have 
been observed In many cases just after the passage. In one or two 
instances material has been found adhering to them which might have 
been interpreted as a tail had no other spermatozoids been observed. 
The adhering substances in these cases seemed to be from the granular 
mucilaginous matter in which the spermatozoids swim. Usually the 
spermatozoids found in the archegonia have assumed their normal 
form and show no suggestion of the extreme pressure they must have 
endured in the process of entering. . 
In conjunction with Mr. E. A. Bessey’ the writer has made some 
interesting observations on the living pollen tubes of Ginkgo mounted 
in 10 and 5 per cent sugar solutions. ‘The whole pollen tube apparatus 
is clearer and much more favorable for observation in the unstained 
condition than that of Zamza. In very many tubes the main features 
of the central cell could be plainly observed. The nucleus corps 
spheriques and the blepharoplasts were plainly visible when tubes were 
cut off and placed in sugar solutions without injury. The nucleolus 
could almost invariably be observed to contain at least one large 
vacuole, and very frequently a number of smaller ones could be 
observed. In one instance a nucleus was observed in a prophase of 
division when the chromatin had collected in a skein. This was an 
absolutely fresh tube and could not be mistaken, being as plain as in 
the fixed and stained material. The nucleoplasm outside of the skein, 
which was composed of large granules and presented a dense appear- 
ance, was clear and finely granular, the only difference between the 
skein and other nucleoplasm seeming to be the larger size of the gran- 
ules in the skein and their greater density. In quite a number of cases 
the blepharoplast could be plainly distinguished, and in one instance 
shown to the writer by Mr. Bessey the contents could be seen to be 
vacuolated or reticular almost as plainly as in the fixed and stained 
material. ‘There can thus be no doubt that the main features brought 
out by fixing and staining in Ginkgo and Zamia are perfectly normal 
and not artifacts. The study of the living material of Ginkgo, which 
should be carried much farther, promises much valuable information, 
particularly in confirming the results obtained by fixing and staining. 
Personally the writer has made no attempt to secure the living and 
1These observations on the living material of Ginkgo were made on material col- 
lected by Mr. E. A. Bessey, one of the writer’s colleagues. He also made many 
interesting observations, a short account of which will be found in Science, February, 
1901. 
