Jan., 1906.] Embryo Sac and Embryo of Cucumis sativus. 
427 
little deviation (Fig. 27) throughout its entire course; but usu- 
ally there is a peculiar and characteristic bulging (Fig. 28) some 
distance above the embryo sac. It spreads out in the surround- 
ing tissue, completely breaking down the cell structure. How- 
ever, before it reaches the sac it again narrows, sometimes to a 
greater extent than elsewhere along its course. After it has 
pierced the sac it turns to one side or widens out into a foot-like 
process. 
The most typical tubes have not only a bulging but decided 
haustoria-like processes (Fig. 29) which extend out into the cell 
structure of the nucellus and in some cases even break through 
the inner integument (Fig. 30). The haustorial prolongations 
appear to act as absorbing and conducting agents for the food 
material of the embryo. Longo reports to have observed these 
processes in his study of cucurbita and believes them correlated 
with the distribution of starch in these parts. He also reports to 
have found in Cucurbita pepo a conducting tissue which the 
pollen tube follows from the stigma to the embryo sac. 
The points of especial interest and peculiarity observed in 
the deveolpment of Cucumis are (1) the long micropyle into 
which extends the long neck of the flask-shaped nucellus, (2) 
the presence of two well developed integuments, (3) the anatro- 
pous ovule with orthotropous embryo, (5) the small size of the 
embryo sac and associated structures in comparison with the 
size of the nucellus, (6) the irregular development of the embryo, 
and (7) the peculiar behavior of the pollen tube. 
The work represented in this paper was carried on under the 
direction of Prof. John H. Schaffner, to whom I wish to express 
my sincere thanks for valuable assistance and suggestions. 
PAPERS CITED. 
1. Longo, Beagio, Richerche sulle Cucurbitaceae e il signi- 
ficato del percorso intercellular (endotropic) del tubetto 
pollinico. R. Accad. der Lincei, 30:523-5-17 pi. 1-6, 1903. 
2. Longo, Beagio, Osservazioni e ricerche sulla nutrizione dell 
enbrione vegetale. Annali Botanica 2:373-396. 1905. 
3. Kirkwood, Joseph, The Comparative Embryology of the 
Cucurbitaceae. Bull. N. Y. Bot. Gar. 3:313-402. 1905. 
