194 BOTANICAL GAZEITE [MARCH 
4. Davis, B. M., The spore mother cell of Anthoceros. Bot. GAZETTE 28:89- 
109. pls. 9, 10. 1899. 
, Nuclear studies in Pellia. Annals of Botany 15:147-180. pls. 10, 
II. 190l. 
6. - , Spore formation in Derbesia. Annals of Botany 22:1-20. ls. 1, 2. 
1908. 
. Lawson, A. A., Some observations on the development of the karyokinetic 
spindle in the pollen mother cell of Cobaea scandens. Proc. Cal. Acad. Sci. 
Bot. III. 1: 169-184. pls. 33-36. 1898 
. ———, Origin of the cones of the multipolar spindle in Gladiolus. Bor. 
Gazerre 30: ai 153. pl. 12. 1900. 
‘ e er Sette of the nuclear membrane to the protoplast. 
Bor. gc 35:305-319. pl. 15. 1903. 
. Mortier, D. M., Beitrige zur Kenntniss der Kerntheilung in den Pollen- 
mutterzellen einiger Dikotylen und Monokotylen. Jahrb. Wiss. Bot. 30: 
169-204. pls. 3-5. 1897. : 
11. Osreruout, W. J. V., Ueber Entstehung der karyokinetischen Spindel bei 
Equisetum. Jahrb. Wise: Bot. 30:159-168. pls. 1, 2. 1897. 
12. SmiTH, R. W., The achromatic spindle in the spore mother cell of Osmunda 
regas. Bot. GAZETTE 30:361-377. pl. 22. 1900. 
EXPLANATION OF PLATE XIII 
All drawings were made with the aid of a camera lucida, using a No. $ ocular 
and a 1.5™™ objective. 
Fic. 1.—Male and female nuclei of Peperomia sintenisii approaching each 
other; each nucleus shows one gears in side facing the other. 
Fic. 2.—Later stage of sa 
Fic. 3.—Male and female vas in contact; each shows two depressions. 
IGS. 4, 5.—T wo sections throng same pair of nuclei, each of which contains 
three depressions. 
Fic. 6.—Early stage of fusion; nuclear membrane has disappeared where 
nuclei have come into contact with each other, causing the entire inclosure of 
one and partial inclosure of two other cytoplasmic globules. 
Fic. 7.—About same stage as fig. 6; one globule entirely, another partially 
inclosed. 
Fic. 8.—Fusion nucleus containing one vesicle of cytoplasm: surrounded by 
a nuclear membrane. 
Fic. 9.—Fusion nucleus containing two vesicles of cytoplasm. 
Fics. 10, 11.—Later stages; the cytoplasm stains less densely. 
Fics. 12-14.—Still later stage; the staining reaction of cytoplasm has com- 
pletely disappeared from one of the vesicles. 
Fics. 15-18.—The contents of the vesicles are indistinguishable from the 
surrounding clear nuclear sa sap. 
Fic. 19.—The membrane around the vesicle i is beginning to disappear. 
Fic. 20.—Later stage in t d the vesicle. 
5. 
“I 
aa 
° 
ty 
