198 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Seeds and Seedlings of Arisaema triphyllum and A. Dracontium.* 

 — R. J. Rennert haB made a comparative study of the seeds and seed- 

 lings in these two species. The seeds are similar, as also are the first 

 stages in germination, but a marked difference obtains in the manner of 

 development of the corm. In A. triphyllum the emergence of the hypo- 

 cotyl is followed by vigorous growth of root and plumule, and it is 

 only after the seedling has separated from the seed that the hypocutyl 

 begins to enlarge to form the corm. In A. Dracontium on the other 

 hand, the enlargement of the hypocotyl begins immediately on its emer- 

 gence from the seed, while the development of root and plumule is 

 retarded. In a large majority of cases the plumule never becomes func- 

 tional, the first assimilating leaf being borne on the corm in the second 

 season. Thus, whereas in A. triphyllum the corm is the product of the 

 photosynthetic activity of the plumule, in A. Dracontium it is the result 

 of the transference of the food-stuffs stored in the endosperm. 



Floral. 



Origin of the Flower.f — L. Nicotra describes the mode of appear- 

 ance and the development of the sepals and petals, and essays to deduce 

 therefrom a theory of anthogenesis. He regards the primitive type of 

 flower as one consisting only of the sexual organs necessary for repro- 

 duction. The absence of a perianth may be primitive or secondary, 

 and the absence or presence of a perianth is a very unsafe ground for 

 classification, since this may occur in all gradations in the course of 

 development of a single family. 



Strengthening and Nourishing System in Flowers.^ — J. Herzog 

 has studied the mechanical relations between the different floral whorls 

 and finds that in actinomorphic flowers with clawed petals a diminution 

 of the petal limb with a shortening and thickening of the claw is corre- 

 lated with a diminution of the mechanical system in the calyx, and vice 

 versa. Also that a corolla of free clawed petals is associated with a 

 stronger calyx than an otherwise similar corolla with a gamopetalous 

 tube. Similarly the strength of the calyx varies with the diameter and 

 length of the corolla-tube, the form of its transverse section, and the 

 thickness of its walls. Flowers of Papilionaceae showed a striking re- 

 lationship between the amount of mechanical tissue in the calyx and 

 that in the lower parts of the remaining floral whorls, the amounts vary- 

 ing inversely in the two cases. The author also finds an increase in 

 the tissues by which the plastic food-stuffs travel, in the androecium and 

 gynaecium as compared with the perianth whorls. 



Staminode-like Structures in Dentaria bulbifera.§ — J. Klein de- 

 scribes staminode-like structures found, under certain conditions, in the 

 flower of this crucifer, often followed by the formation of peculiar 

 structures from the base of the pistil after the other parts of the flower 

 have fallen. As Dentaria bulbffera is dependent on insects for cross- 

 pollination, and as this does not take place in damp and shady situations, 

 and as no siliquae were formed on the plants which bore these peculiar 



* Bull. Torrey Bot. Club, xxix. (1902) pp. 37-54. 

 t Atti r. Accad. Sci. Acireale, x. (1901) pp. 2-30. 

 j Ber. Deutsch. Bot. Ges., xix. (1901) pp. 564-9. 

 § Tom. cit., pp. 421-8 (1 pi.). 



