518 MacDougal: Symbiosis and Saprophytism 



with the micro-spectroscope. The free portion representing the 

 lamina is i to 2 cm. in length, and the outer dorsal surface is pro- 

 vided with stomata, the guard cells of which are motile and con- 

 tain starch (Plate 369, Fig. 5). The possibility that the guard 

 cells may contain a small amount of chlorophyll is not excluded, 

 though it could not be detected by ordinary tests in the specimens 

 examined. The epidermis is composed of muriform cells with the 

 outer walls convex and not cuticularized. The mesophyll consists 

 of two layers of irregularly globoid elements rich in protoplasm, 

 and separated by large air-spaces. A third layer of thin -walled 

 elements, cylindrical in form are to be found lateral to the simple 

 fibrovascular bundles. This tissue is devoid of protoplasm and 

 may serve for the storage of water. The sclerenchyma sheath is 

 incomplete at the point of contact with this supposed storage tis- 

 sue, thus permitting the ready passage of water between the xylem 

 and the thin-walled cells. 



The degeneration of the leaf is seen to consist in the loss of 

 chlorophyll, the lack of differentiation of the mesophyll, and the 

 reduction of the surface. This degeneration has been accompanied 

 by the development of a tissue for the storage of water, and by the 

 retention of the stomata. Ccplialanthcra is to be added to the list 

 of chlorophylless species furnished with motile stomata. 



General Considerations 

 It is evident that the mycorhiza of Ccplialanthcra is to be con- 

 sidered as adventitious or accidental in its occurrence. In a large 

 number of ectotropic forms the fungus gains entrance to the un- 

 derground organ very early in its development, and then keeps 

 pace with its growth. In this instance, however, it is found only 

 in certain regions, and might be mistaken for a parasite were it not 

 for its characteristic vesicles or organs of interchange. The com- 

 paratively small area of the mycorhizal structures suggests that 

 Ceplialanthera is capable of absorbing largely from the humous 

 products independently. 



Calypso bulhosa (L.) Oakcs 

 The author has called attention to the occurrence of adventi- 

 tious mycorhiza in Calypso {\ i), and cited Lundstrom's description 



