308 BOTANICAL GAZETTE [ocToBER 
one of the individual spines figured. The second and third:single spines 
figured show irregular cavities toward the apex which are apparently 
cut off from the cell cavity, and the third spine figured gives a good idea 
of the papillose character of those adjacent cells in which these processes 
are not prominently developed. 
In the area included in fig. 1 are three of the curious stomatal open- 
ings which apparently characterize the genus Frenelopsis. These are 
circular in outline and about 0.03 mm. in diameter. They are very 
numerous, but whether they are localized on certain portions of the 
branches which perform the functions of leaves in this genus, or whether 
they are uniformly distributed on the annual shoots, could not be deter- 
mined. They consist of five or six guard cells arranged around the 
Fic. 2 
central stomatal opening. These cells are much thinner-walled than 
the epidermal cells. In form they are relatively slender distally and 
broad proximally. As viewed through the microscope, they are darker 
colored around the stomatal opening and peripherally they are lighter. 
Since structural material is not available, their exact attitude is made out 
with difficulty. Their outer centrally directed ends come into focus 
at about the same time as do the outer ends of the longer spinelike pro 
cesses, or very soon after, while their inner broad ends are visible after 
the epidermal cells have gone out of focus; hence it is obvious that they 
are inclined toward each other and project outward for a considerable 
distance from beneath the surrounding epidermal cells. It is believ 
that fig. 2, which is a diagrammatical drawing of a single group of these 
guard cells and two adjacent epidermal cells viewed in a radial aie 
of a twig, gives an accurate idea of their arrangement and proportions. . 
