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IOWA ACADEMY OE SCIENCES. 
The mestome bundles are of two types; first, those that 
resemble the open bundles of other species, only that in this 
case they are surrounded by thick walled parenchyma outside 
of which, on two sides occur the chlorophyll bearing paren- 
chyma cells (c b p); second, those that are entirely closed. 
The mestome bundles are differently arranged in this species, 
a small mestome bundle occurs beneath the bulliform cells, 
this bundle is smaller than the one occurring between the bulli- 
form cells, but is of the same type. Surrounding the bundles 
of the first type are small chlorophyll bearing cells and more 
numerous than in the other species studied. The chlorophyll 
bearing parenchyma cells surrounding those of the second type 
are larger than those of the first type, but not as large as those 
of the other type. In this species the leptome and hadrome 
are in immediate contact while thick walled parenchyma cells 
surround both. 
The stereome is found on the upper and lower surface of all 
mestome bundles of the first type and separated from leptome 
and hadrome by thick walled parenchyma. Stereome does not 
occur around the mestome bundles beneath the bulliform cells. 
The mestome bundles between the bulliform cells are always 
closed below and sometimes entirely so. 
The mesophyll consists of both elongated and round cells 
bordering on the chlorophyll bearing parenchyma. 
COMPARISON. 
A comparison of the two genera shows that in the genus 
Sporobolus the cuticle and bell walls are much more strongly 
developed than in the genus Panicum. 
The mestome bundles in Panicum are more numerous than 
in Sporobolus. The epidermal cells in Sporobolus are uniform 
in size, in Panicum variations occur in different species, while 
in P. crus-galli, the epidermal cells on both sides of the median 
nerve are smaller than elsewhere on the leaf. 
The bulliform cells are larger and more numerous in Sporo- 
bolus than in Panicum. 
CONCLUSIONS. 
We feel safe in concludiug from our study of these genera 
that the anatomical characters are marked and constant enough 
to readily enable one to distinguish the species, and along with 
the work of others it shows that anatomical characters may be 
u^ed as a basis for the separation of genera and some species. 
