78 KANSAS UNIVERSITY SCIENCE BULLETIN. 



embryo sac is narrow and the suspensor is very long. There is 

 no antipodal canal, but the endosperm tissue bends toward the 

 terminus of the vascular bundle in the form of a process. 



Nepeta cataria. 

 The haustorium of Nepeta cataria is coenocytic, and contains 

 four nuclei that occupy a more or less definite position at its 

 base or near the place where the suspensor passes into the con- 

 striction (fig. 21). The haustorium is relatively small, con- 

 taining much less than half the length of the suspensor. 



Dracocephalum sp. 

 This varies from the other species of Labiatse examined in 

 the character of the outline of the endosperm tissue. In the 

 other species this tissue enlarges quite uniformly, presenting 

 a smooth or entire outline when sectioned. The outgrowths 

 in Dracocephalum have no definite position or form and hence 

 are not to be regarded as other than integral portions of the 

 endosperm tissue and not haustoria (fig. 22) . The haustorium 

 is much elongated, as is the endosperm tissue. The embryo lies 

 in the upper portion of the latter, being attached at the end of 

 a very long suspensor. 



Scutellaria parvula. 

 The bent embryo sac of Scutellaria, resulting in a bent em- 

 bryo in the ripe seed, is of course well known to taxonomists. 

 It conforms to the other species in Labiatse in possessing a 

 haustorium, but located, as it is, at the extreme tip of the ovule, 

 its growth is greatly limited, so that it remains small (fig. 23). 

 The endosperm is elongated and tapers at the base into a hook- 

 like process whose end lies near the terminus of the vascular 

 bundle. 



DISCUSSION AND CONCLUSIONS. 



In a large number of plants, especially those in which two 

 integuments are present, the embryo sac assumes a somewhat 

 elliptical or oval form in longitudinal section, with an approxi- 

 mately entire outline. The nutrition designed for growth of 

 the endosperm may be absorbed fairly uniformly over the en- 

 tire surface of the sac, or it may be absorbed more rapidly at 

 one point than at other points, but in either case the elliptical 

 or oval outline is maintained. If added organs mean increased 

 specialization, then embryo sacs of the t5npe just mentioned. 



