Spermatophytes Gymnosperms 253 



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 

 anilin blue, some in safranin and light green, and some in iodine 

 green and acid fuchsin. A single preparation with sections stained 

 in various ways will repay a careful study. Of course, every prepara- 

 tion should contain transverse, longitudinal radial and longitudinal 

 tangential sections. 



The root. -The primary root should be studied in the embryo 

 while it is still contained in the seed. Collect material in September, 

 October, or at any later date. If material is collected in winter, the 

 seeds should be soaked in water for a day or two before fixing. In 

 any case, remove the testa and cut a thin slab from opposite sides 

 of the endosperm to facilitate fixing and infiltration. For secondary 

 roots and also for the structure of the stele in the primary root, 

 germinate the seeds and fix material after the hypocotyl has reached 

 a length of 3 or 4 cm. The seeds of Pinus edulis, commonly called 

 Pinon, or edible pine, can be obtained in most cities. They are 

 particularly good for a study of the mature embryo and the seedling. 



The older roots are treated like the stems. 



The leaves. The leaves of our common gymnosperms cut readily 

 in paraffin while they are young and tender, but as they approach 

 maturity it is a fruitless task to attempt paraffin sections. 



Good sections may be obtained in great quantities with little 

 trouble by the following method: Make a bunch of the needles as 

 large as one's little finger, wrap them firmly together with a string, 

 allowing about f inch of the bunch to project above the wrapping; 

 then fasten the whole in a sliding microtome or a hand microtome, 

 and every stroke of the razor will give twenty or thirty sections, some 

 of which will surely be good. -As the sections are cut, put them into 

 95 per cent alcohol; after 5 or 10 minutes, transfer to 70 per cent 

 alcohol, where they should remain for 15 or 20 minutes to remove 

 the chlorophyll; then transfer to the stain. 



Spermatogenesis. In October the clusters of staminate cones 

 which are to shed their pollen in the coming spring are already quite 

 conspicuous. The cones should be picked off separately, and the 

 scales should be carefully removed so as to expose the delicate 



