CONTRIBUTION TO THE LIFE HISTORY OF SAGIT- 
TARIA VARIABILIS.? 
JoHN H. SCHAFFNER. 
(WITH PLATES XX—XXVI) 
Tue following work upon Sagittaria was begun in October 1896, 
and is a continuation of my former work on Alisma Plantago,* to 
which paper frequent reference will be made for comparison. 
So far as the writer knows, no special work has been done upon 
the gametophyte generation of Sagittaria, or upon its embry- 
ology. The material used was killed ina solution of chrom-acetic 
acid and preserved in 70 per cent. alcohol, and the usual methods 
of imbedding in paraffin and staining on the slide were employed. 
The stain used for the greater part of the work was a double 
stain of anilin-safranin and gentian-violet. 
The investigation was carried on under the direction of 
Dr. John M. Coulter, to whom I here express my thanks for 
assistance and criticism. 
The flowers of Sagittaria variabilis are all monosporangiate, 
but frequently there are abortive carpels at the center of the 
staminate flower. Some varieties are moncecious and others 
dicecious. The carpels, which become achenes, are spirally 
arranged upon a very globose receptacle, as are also the 
stamens. The ovules are apotropous. In the earlier stages 
they are anatropous, but later they become strongly campyl- 
otropous, so that the mature embryo is bent double and becomes 
horseshoe shaped. Both the staminate and carpellate — 
have nectaries which are active during the blooming perio 
_ The nectaries are situated around the base of the flower, between 
eti ies Shae to be simply me : 
the carpels and the 
ba ae RCo MEE ae eh ey. 43 wk 
of Alisma exer ig Gaz. ae 123-132. 1896. 
fa a 
