- 1900) | CURRENT LITERATURE 357 
plant uses efficiently for the proper gaseous exchanges also. (M. Devaux 
_ promises a further memoir on the general aeration of the plant by lenti- 
Finally, lenticels are defined as small limited regions of the superficial 
_ parenchyma in continual proliferation and continual development, capable of 
hypertrophy or of cicatrization, according to the conditions of external or 
_ internal humidity.— C. R. B ; 
ARECENT PAPER? on the embryology of Taxus daccata fills in some of 
ofthe gaps in previous accounts. The writer secured an abundance of wild 
material, but employed rather primitive methods in making his preparations, 
fixing in absolute alcohol, imbedding in celloidin, and staining in haema- 
toxylin. The following is a brief résumé of his work. 
The origin of the aril shows it to be a second integument. In tracing the 
development of the embryo sac the author was not able to get the earliest 
Stages. The two, four, and eight-celled stages of the embryo sac were not 
observed, but many sacs were observed in later stages. Free nuclear 
1 _ tivision continues until there are about 256 free nuclei in the sac (the eighth 
division), when cell walls begin to appear. These cells rarely contain more 
than one nucleus, and have a regular six-sided appearance in optical section. 
ln the later stages of endosperm formation the cells are often multinucleate. 
The formation of archegonia begins at the end of May or the first of June, 
) Dut archegonia in very different stages of development are soon found in the 
a Same prothallium, even embryos and young archegonia often appearing 
ether. The usual number of archegonia is from five to eight, but nine, 
"en, and even eleven were observed. Pollination occurs from the beginning 
‘othe middle of March, and there is no so-called pollen chamber. By the 
of May three nuclei can be seen in the pollen tube, the tube nucleus, 
the huclei of the stalk cell and of the generative cell. Shortly before 
“vation occurs the generative cell divides into two very unequal cells. 
“ttilization takes place about the first of June. There may be several 
tubes, and several “archegonia” may be fertilized. The sex nuclei, 
ich are of about the same size, come into contact and then sink to the 
of the archegonium, where fusion takes place. Nuclear division then 
: ang until there are from ten to sixteen free nuclei at me base of the 
Pte ( ter which the free cells become arranged into ters, ; 
Fosette’’), the middle tier, consisting of suspensor cells usually 
ber but Sometimes more, and the lower tier, which is the embryo proper. 
long to a single 
ase three were 
F 
six in 
rest here are normally two cotyledons, but in one ¢ 
3 -—CHARLES J, CHAMBERLAIN. 
PR 
ete, L.: 
Taxy Beitrige zur Kenntniss der Endospermbildung und zur Embryologie 
+4 
bacrata L, Flora 86 : 241-288. pis. 15-79. 1899. 
