296 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Nuttaliii , C. rimdaris (pi. 18, fig. 57, where the origin and 
transverse division of the trichoblast is seen). Dulichium spct- 
thaceum , Eleocharis palustris, Eriophorum alpinum, Firnbri- 
stylis autumnalis , Hemicarpha subsquarrosa , Isolepis gracilis , 
Kilingia pumila, Rhynchospora fusca (pi. 18, fig. 62), Scirpus 
airovirens, S. debilis, S. maritimus (pi. 18, figs. 63, 64), S. 
setaceus. 
Gramineae. The trichoblastic elements may be numerous, short 
in comparison with the other cells of the epidermis, and thus 
readily distinguished as in Sorghum vidgare , Anthoxanthum 
odoratum, Panicum sanguinale , and various species of Poa. 
On the other hand the origin of the hair-cells is often difficult 
to make out. The differentiating division results in two seg¬ 
ments of about equal size, and of nearly similar contents. The 
atrichomic cell may subsequently divide. In the mature epider¬ 
mis the trichomes and atrichomic cells do not differ much. 
Differentiation is less pronounced, and seems in reality to be 
passing away. In some members of the group, in fact, the 
entire epidermis may be piliferous; the habit of setting apart 
special cells for the bearing of root-hairs has been lost. Oryzct 
sativa is one of the very few examples found in a large number 
of grasses examined in which the entire loss of the trichoblastic 
character was definitely ascertained. The following show 
specialized hair-cells: Agrostis Steeveni, A. stolonifera , A. 
vulgaris , Alopecurus occidentcdis , Andropogon nutans , Antho¬ 
xanthum odoratum, Asprella hystrix , Arena sterilis , Briza 
gracilis , Bromus asper , B. albidus, B. giganteus , B. pur gems , 
B. Richardsoni , Calamagrostis hyperborea, C. montanensis, 
Chloris elegans, Deschampsia ccespitosa, Elymus virginicus , 
Festuca ampla , F. duriuscida, F. ovina, F. arundinacea (pi. 
18, fig. 68), F. pratensis, Holcus lanatus , Hordeum nodosum , 
II. pusillum , Folium italicum , Miscanthus candensatus , Pani¬ 
cum sanguinale , /k saccharatum , Pappapliorum Wrightii , 
Paspcdum tenellum , Phalaris canadensis , 7k paradoxa , 
Phleum asperum , sp., 7*. laevigata , 7\ violacea (pi- 
18, fig. 69), Polypogon monspeliensis , Puccinellia airoides. 
Sorghum vulgare, Sporobolus airoides , $. cryptandrus. 
