TRIPHYLLUM AND ArISAEMA DrACONTIUM 53 



Owing to the lack. of time and material the development of the 

 corm of Spatliycnia within the seed could not be traced but an ex- 

 amination of the literature of the subject brought out the fact 

 that many aroids manifest a tendency to carry on the development 

 of the plant as far as possible before actual germination, /. c, 

 emergence from the seed and development of assimilatory organs 



occurs.* 



Summary 



The seeds of the two species present only a few unimportant 

 differences in shape. In histological structure they are similar. 

 The embryos are comparatively small and are imbedded in a co- 

 pious farinaceous endosperm. The only essential distinction be- 

 tween them consists in the slightly greater amount of food material 

 in the seed of A. Dracontiiim, the extra procambium strand of its 

 cotyledon and the weaker development of procambium in the 

 plumule of its resting embryo. The first .stages of the germina- 

 tion of the two seeds are of the same character and consist in the 

 emergence of the hypocotyl and stem- bud from the seed coats at 

 the micropyle, by means of the elongation of the cotyledon. 



As the development of the seedlings proceeds, the production 

 of roots and a plumule takes precedence in A. triphvllmn while in 

 A. Dracontiiun the enlargement of the hypocotyl begins at once 

 and the growth of the root and plumule is retarded. This pre- 

 cocious development of the corm often takes place to such a de- 

 gree as to entirely inhibit the production of a functional plumule. 

 The same differences between the two species in regard to the 

 fibrovascular development is exhibited by the seedlings as is dis- 

 played by the resting embryo. The structure of the stem-bud 

 which develops upon the corm during the first season's growth 

 is absolutely the same in both species. 



The seedling of A. Dracontium is diverging from what seems to 

 be the normal type of germination in Arisaema, i. c, the develop- 

 ment of an assimilatory plumule and the production of a corm by 

 means of the product of the photosynthetic activity of this organ, 

 and is tending to produce a corm without the aid of a plumule by 

 the direct transfer of the food material of the endosperm to the 



* Engler. Monographiae Phanerogamarum. Araceae, ii : 34, 35- 

 Griffith. Trans. Linn. Soc. 20: 274-276. 1847. 



