63 



Plant secretory cells which yield watery exudates are in 

 general termed hydathodes bj'^ Haberlandt. (d) In the present 

 irstance it is evident that the epidermal cell is the hydathode 

 ana the process merely a conduit, in which the extremity is 

 closed. 



Figure 3. 



An epidermal cell showing a process very highly magnified. 



A hydathode resembling the one found in Spartina stricta 

 has been described by Heberlandt (e). It is found in Gono- 

 erryum, one of the Icacinaceae. A tubular papilla rises from the 

 epidermal cell, as in Spartina, but instead of the end being 

 cicsed by a cellulose wall, it is closed by a mucilaginous cap in 

 the center of which the canal opens. After a heavy rain the cap 

 may be washed away, when the canal is unstopped. Haberlandt 

 says that the function of this hydathode is the same as that of 

 the ordinary water pore in that it serves as a means of escape 

 of water in liquid form, or when water in gaseous form can not 

 escape by the usual process of transpiration. He says that there 

 i . no protoplasmic contents of the canal in the Gonocaryum hyda- 

 thode. If there is any protoplasm in the canal of the Spartina 

 hydathode it is not recognizable by an ordinary oil-immersion 

 lens. The secretion of salty solutions by plants is generally as- 

 sociated with the metabolism of xerophytes, or plants living in 



(d) 

 (e) 



Phj'siologische Pflanzenanatomie. 

 loc. clt. 



