68 A. H. Graves, The Morphology of Ruppia Maritima. 
descriptions and figures (Griffith, 1851, I-IL; Irmisch, 1858; Hille- 
brand, 1888; Ascherson, 1889; Sauvageau, 1891, II; Hooker, 1894; 
Roze, 1894; Britton, 1907), four species may be safely recognized ; 
namely, R. maritima L., R. rostellata Koch, R. brachypus Gay, and 
R. occidentalis Wats. 
All of the material for the present work was collected in tidal 
ditches in Fort Hale Park, near New Haven, Conn. Here it grows 
in abundance, forming large tufts with its grass-like leaves, which 
follow easily the direction of the current. At extreme low tide a 
large portion of the plant floats, but at high tide it is completely 
submerged. The period of flowering commences in June and con- 
tinues until the severe frosts in autumn, up to which time, even in 
October, I have gathered flowers in good condition. 
The material was killed either in chromacetic acid, Flemming’s 
solution, or Keyser’s fluid. The first seemed the best, although the 
others gave good results. Several stains were used: for general 
work haematoxylin and erythrosin; for cytological study in the 
development of the male and female gametophytes, &c., and the 
embryo, the triple stain was used with excellent results. For the 
latter investigations Heidenhain’s iron haematoxylin was also found 
to be good. In all, about 20,000 microtome sections were cut of 
the different parts of the plant. For all of the microtechnique 
Chamberlain's “ Methods in Plant Histology” was found invaluable, 
and in all preparations the directions given therein were closely 
followed. 
I would like to avail myself of this opportunity to express my 
_ gratitude to Professor Alexander W. Evans, Eaton Professor ot 
Botany in Yale University, for the great interest he has taken in 
the work and for the invaluable criticism and suggestions which 
he has been ever ready to give. I desire also to thank Professor 
W. R. Coe, Professor J. W. Toumey, and Dr. A. L. Dean, of Yale 
University, for their kindness in offering suggestions, material, &c. 
