1905] FRYE & BLODGETT—LIFE HISTORY OF APOCYNUM > 53 
4. ROSENBERG, O., Ueber die Pollenbildung von Zostera. Meddel. Stock- 
holms Hégsk. Bot. Inst. p. 21. 1gor. : 
ul 
.. STRASBURGER, E., Neue Untersuchungen iiber den Befruchtungsvorgang 
ei den Pidnero gare p- 31. Jena. 1884. 
6. Kuntu, P., Handbuch oF Bliithenbiologie 27:70. 1899. 
7. BILLINGS, F. H., Beitrige zur Kenntniss der Samenentwickelung. Flora 
88: 253-318. Igor. 
EXPLANATION OF PLATE II. 
All figures were drawn with a camera lucida unless otherwise stated, and a 
Leitz 1-12 oil immersion objective was used for all figures requiring high magni- 
fication. The figures have been reduced to one-half the —— drawings, 
to which the indicated magnifications apply. 
1G. 1. Longitudinal section of the flgwer;- semi-diagramatic: ca, calyx; 
co, corolla; r, ridge; g, gland;, s, stamen; ap, appendage; sp, sporangium; 
b, beard; h, head; st, stigma. 
Fic. 2. Abaxial view of stamen: ap, appendages; without camera lucida. 
Fic. 3. Lateral view of stamen: ap, appendages; /, head; without camera 
lucida. 
- Frc. 4. Longitudinal section of anther showing origin of primary parietal 
layer. XI 
Fic. 5. i cuihaliaal section of anther: s, primary sporogenous cells; , ¢, 
tapetum. X 2650 
Fic. 6. Cross ees of anther: ¢, tapetum; s, primary sporogenous cells. 
X IIIO. 
Fic. 7. Microspore mother cell before tetrad division. X 3300 
Fic. 8. Microspore daughter cells in simultaneous division. 3300. 
Fic. 9. Three pollen grains from a mother cell. 2250. 
Fics. 10-13. Various arrangement of pollen grains in tetrads. 2250. 
Fic. 14. Pollen grain: ¢, tube nucleus; g, generative cell. X 2650. 
Fic. 15. Section of ovule showing archesporial cell enlarged and functioning 
as primary sporogenous cell; single integument; nucellus one layer of cells. 
2270. 
Fic. 16. Same as fig. 15; integument closing. 1400. 
Fic. 17. Four megaspores; first and third diciyeegrating; m, micropylar 
end. X 3300. 
Fic. 18. Four megaspores; first two disintegrating; m, micropylar end. 
X 3300. 
Fic. 19. Four megaspores and nucellus; first three disintegrating. 3300. 
