21 



ai-coiiip.iiiic(l hy (liiniiiut ion in tlie size of the cells, is manifest 

 Avlu'ii a ('(niiparisoii of two sides of a pulvinus is made. In 

 order to show this elearly. i>ulviiii exposed to full sunlight and 



Figure 9. — Camera lucida drawings of the cortex on opposite sides of a pul- 

 vinus in full sunlight. The upper figure is from the concave or illumi- 

 nated side; the lower figure is from the under or convex side. 



to darkness (sleep position) were used. These were abscised 

 in the field and placed into various killing tiuids as Carnoy's 

 fluid, alcoholic solution of corrosive sublimate, and chromo-acetic 

 acid. After embedding in paraffine. sections were made longi- 

 tudinally. 



A comparison in the size of ihc rdls on th<> upix-r and lower 

 sides of the pulviiii is ivjidjly ol»1;iin<Ml from Figures 9 and 10. 

 The cells on the concave sides in both cases are narrower than 



