SERPMATOPHYTES—GYMNOSPERMS 
279 
ent species and even for the same species in different regions; P. 
LariciOj at Chicago, sheds pollen about the middle of June, but P. 
maritima at Auckland, New Zealand, sheds its pollen about the 
first of October. After a year’s collecting in any region, there should 
be no difficulty, since the dates do not vary much from year to year. 
The Vegetative Structures.—The stem, root, and leaf will be 
treated separately. 
The stem .—The vascular cylinder is an endarch siphonostele, a 
type which, with few exceptions, is found throughout the living 
gymnosperms. 
The young stem in its first year’s growth is green and soft and is 
easily cut in paraffin. The best time to collect material is soon after 
the young shoot has emerged from the bud scales in the spring. 
Resinous material, like these young stems, do not fix well in aqueous 
media. With a thin safety-razor blade, cut the stem transversely 
into pieces about 5 mm. in length; fix in formalin alcohol, imbed in 
paraffin, and stain in safranin and light green. Longitudinal sections 
of the buds in winter or early spring condition are instructive for 
comparison with longitudinal sections of the ovulate cone. Trim 
away most of the bud scales and cut a slab from opposite sides, 
leaving a piece 2 or 3 mm. thick to be imbedded. The bud, and also 
selected pieces of the young stem, will show the structure of the young 
leaf. Later in the season, even the first year’s shoot should be cut 
without imbedding. The two- and three-year shoots and all older 
material can be cut freehand, without imbedding, and, preferably, 
before fixing. Such sections are transferred directly from the knife to 
95 per cent alcohol. 
For the structure of the adult stem, select a clear board and, for 
transverse sections, cut out pieces about 2 cm. long and 6 to 10 mm. 
square; for longitudinal sections, use pieces about 2 cm. long, with 
5 and 10 mm. for the other two faces. Cut from the face which will 
give sections 5X10 mm. Orient carefully, so that the longitudinal 
radial sections shall be exactly parallel with the rays, and the longi¬ 
tudinal tangential sections exactly tangential to the rays. Leave the 
sections in 95 per cent alcohol for 15 or 20 minutes before staining. 
Stain for at least 24 hours in safranin, extract the stain until only a 
faint red color is left in the cellulose walls, and then stain in Dela- 
field’s haematoxylin. Stain some of the sections in safranin and 
crystal-violet and some in safranin and light green. Of course, 
