a 
1899 ] LIFE.HISTORY OF LEMNA MINOR 65 
paratively few cases, the rule being that disorganization stops 
the process at some stage. This disorganization first affects the 
antipodal end of the sac. In sacs which have succeeded in 
developing endosperm we find it next attacked; and last to 
succumb to unfavorable conditions is the egg apparatus. 
13. In case the polar nuclei fail to fuse one or both of them 
may develop endosperm without fusion. 
14. Owing to the above conditions there is great paucity of 
seeds, not enough having been found to determine the homologies 
of the sporophyte. 
15. The winter buds are summer buds which have failed to 
develop sufficient air spaces and gases to float them, and hence 
sink. When conditions become favorable again such are devel- 
oped and they again come to the surface. 
16. L. minor seems to have descended from terrestrial forms, 
and has not succeeded in adjusting to a water environment the 
processes involved in developing seeds. 
In closing I wish to express my thanks to Dr. John M. Coulter 
and Dr. Charles J. Chamberlain for many valuable suggestions 
and criticisms given during the progress of this work. 
THE UNIVERSITY OF CHICAGO. 
BIBLIOGRAPHY. 
1. 1867. KAUFMANN, —: Ueber die aufstiegenden Axen einiger Lem- 
nace. Russisch, In der Arbeiten der Versammlung der russischer Natur- 
forscher zu St. Petersburg, 
2. ———. HEGELMAIER, F.; Lemnacez. Flora Brasiliensis 76: 1-24. 
3- 1868. KAUFMANN, —: Entwickelungsgeschichtliche Untersuchungen 
iiber die Lemnaceen. Bot, Zeit. 26 : 382-384. 
4. 1868. HEGELMArIER, F.: Die Lemnaceen. Eine monographische 
Untersuchungen. Leipzig. 
5- 1870. HANSTEIN, JOHANNES: Die Entwickelung des Keimes der 
Monokotylen und Dikotylen. Botanische Abhandl. aus dem’ Gebiet der 
Morph. u. Physiol. 1: 1-112, 
6. 1871. HEGELMAIER, F.: Die Fructificationsteile von Spirodela. Bot 
Zeit. 29: 621-629, 645-666. 
7- 1876. EICHLER, A. W.: Bliitendiagramme 1 : 73-80. 
