TRIPHYLLUM AND ArISAEMA DrACONTIUM 39 



Dracontiinn has the lar<^cr seed. The surface of both seeds is 

 finely pitted and sometimes minute reddish spots are to be seen 

 upon them. A. tripJiylltiui has a yellowish color and A. Dracon- 

 tiinn a reddish-yellow blush. This color is due to substances in 

 the wall of the inner coat of the seed, as the testa is translucent. 



In the general microscopic structure the seeds present only 

 slight dissimilarities. The outermost row of cells in the testa of 

 both species are brick-shaped and are set close together with their 

 long axes at right angles to the radius of the seed. In both 

 the walls of this outer row of cells are mucila<rinous, swelline 

 greatly when they come in contact with water. In A. Dracontitim 

 they are slightly larger and their outer walls are considerably 

 thicker. A cuticle covers this row of cells in both species. Some 

 of tile cells below the outer row of the testa contain tannin, 

 others are filled with mucilage in which raphide cells are im- 

 bedded, still others have a red coloring matter within them. It 

 is to these latter cells that the dotted appearance sometimes noted 

 on the seeds is due. The tegmen consists of three rows of tabu- 

 lar cells with very thick mucilaginous walls. In A. Dracontitim 

 these walls are orange -colored, and in A. triphylluni yellowish in 

 color and so serve to give each seed its distinctive appearance. 

 There is a cutinized lamella on either side of the tegmen cells. 



The seeds of both plants are orthotropous and the embryo is 

 imbedded in an abundant endosperm. In A. triphyllum the endo- 

 sperm appears entirely homogeneous to the naked eye, while in A. 

 Dracontiiim there is a horny layer next the seed coats. Upon mi- 

 croscopic examination, however, but slight differences are evident. 

 The outer portion of the endosperm of A. Dracontiiun consists of 

 3 to 5 rows of cubical aleurone cells with walls capable of great 

 swelling in water. These cells contain granular proteid globules, 

 a single crystalloid, and also a small amount of fat. The aleurone 

 cells of A. triphylluni are of exactly the same character, but are 

 generally only from two to four rows deep, and also a trifle smaller. 

 Within the layers of aleurone cells, making up by far the greater 

 part of the endosperm, are large starch-bearing cells which have 

 thin cellulose walls. Numerous crystalloids are imbedded in the 

 starch of these cells. These crystalloids are slightly more nu- 

 merous in the seeds of A. Dracontiinn. In both cases, however, 



