MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. I31 



Opuntia Opuntia (L.) Coult. 

 A number of fronds of Opuntia Opuntia were laid flat on moist 

 soil in the dark room, in November, 1901, and had developed cylin- 

 drical or compressed stems, which were slightly longer than the 

 normal by January 6, 1902. The leaves, which are subulate and 

 fall off early in the normal, were of an attenuated ovoid form, being 

 drawn down to a very small diameter both at the base and apex. 

 These leaves persisted until the etiolated stems began to show signs 

 of deterioration, when they were easily detachable. 



Fig. 87. Opuntia. Prostrate normal frond, from which arise etiolated stems. 



Marked deviations from the normal were to be seen in the struc- 

 ture of the leaves. Numerous multicellular hairs were found around 

 the leaves, but very few bristles were to be seen. The epidermal 

 cells including the stomata were reduced in size in etiolated plants, 

 and the arrangement of outer layers rich in chlorophyl with their 



