594 SUMMARY OF CURRENT RESEARCHES RELATING TO 



free energids of the egg-apparatus of the Angiosperms have a special 

 physiological function, and that when this function is no longer needed, 

 as in Dicrsea, the parts are not formed. The Podostemacese have no 

 endosperm, and shortly after fertilization the embryo breaks through the 

 embryo-sac, and by means of a long suspensor passes into the nucellar 

 cavity, and then sends out a large haustorial cell into the tissues of the 

 funicle and outer integuments. This direct feeding of the embyro 

 probably accounts for the rapid ripening of the seed. A somewhat 

 similar condition is found in the Orchidaceag. The author remarks 

 upon the suppression of a generation resulting from the direct feeding 

 of the embryo, and shows that the difference here is scarcely less than 

 that between Angiosperms and Gymnosperms ; he regards it as suffici- 

 ently important to be the possible starting point of a new race of plants 

 in which direct feeding of the embryo shall be the general rule. 



General. 



Mycorhiza in the Asclepiadacess.* — E. Busich has studied eighteen 

 species of Asclepiadacea?, and finds that endotropic mycorhiza are of 

 frequent occurrence, being entirely absent in only four cases. They 

 appear to be specially characteristic of succulent species, and have the 

 hyphse, vesicles, etc. of the common endotropic fungi. Some of the 

 vesicles have a peculiar knotted structure, and in addition to those 

 formed within the root, other organs are formed outside which must be 

 regarded as vesicles, and which are capable of re-infecting the root. 

 Thus these vesicles appear to be a special form of reproductive organ. 

 Cells containing crystals of calcium oxalate are not found to be immune. 

 Infected plants give no nitrate-reaction such as is given by non-infected 

 plants, and this result is especially well marked in conducting tissues, 

 thus confirming Stahl's opinion that mycorhiza are characteristic of 

 plants having a reduced flow of water. 



Morphology of the Chenopodiacese.t — F. M. Cohn has studied the 

 morphology and development of the flower of several species of the 

 Ohenopodiacese, and finds that the typical flowers of this family are 

 pentamerous, and all those which differ in this respect are to be regarded 

 as having been derived from a pentamerous ancestor. Eichler's expla- 

 nation of the origin of each individual flower proved to be too artificial. 

 The carpels may be reduced to two and the perianth and androecium 

 may disappear entirely, but the perianth is usually less liable to reduction 

 than the stamens. The flowers of AtripUx hortensis lend some support 

 to Wettstein's theory as to the origin of the flowers of the Angiosperms. 

 A variation from the typical radial arrangement is found in Corispermimi, 

 where the flower is dorsiventral and l)oth perianth and stamens may be 

 entirely absent, although the stamens here have a stronger tendency to 

 resist reduction. Goebel's theory as to an arrangement of paired leaves 

 is supported by the flowers of this family. The different forms of fruit 



* Verb. ZooL Bot. Gesell. Wien, Ixiii. (1913) pp. 240-64 (3 pis.), 

 t Flora, vi. (1913) pp. 51-89 (27 figs.). 



