40 THe Microscope, Se foie 
the constituent filaments becoming shorter as they approach the 
lateral margins of the processes. Hach extinal process is thus basally 
surrounded, while the remainder of the extine is entirely naked, or 
very minutely villous, the surface of the pollen grain therefore pre- 
senting an unusually beautiful aspect. The longest of the villi 
measure about ;;; inch in length. (Fig. 11). 
Small rounded papill arise from the intine by broad bases and 
protrude their evenly convex extremities slightly above the surface 
of the extine (Fig. 12). Their height is about z55 inch; their 
diameter, <357 tO s7ss- 
The hyaline processes of the extine consist of a cylindrical lower 
region forming about one-half of the length of the appendage, when 
it suddenly tapers to the pa (Fig. 13). Their length is 33';5 inch; 
the greatest width about 77137. 
6730 
IPOMGA SAGITTATA, CAY. 
The structure is here that of the pollen of the sweet potato, so 
far as the extinal processes are concerned, and of that of J. pandu- 
rata in connection with the villi of the surface. The former are 
gay inch in length. The rounded papille of the intine measure 
about =';,; inch in diameter, the spherical pollen grains themselves 
a0 
ziz, the last mentioned measurement of the grains of the sweet 
potato being 1; inch, and of I. pandurata about z{> inch. 
JACQUEMONTIA TAMNIFOLIA, GRISEB. 
Here again I can say scarcely more than that the pollen bears 
so close a resemblance to that of the Ipomc examined, that it is 
hardly distinguishable. The general surface of the extine is finely 
hispidulous, the velvety growth measuring about ;34;5 inch in 
length. The longer hyaline processes are simply conical in form, 
rising from a base about ;;5 inch in width, and tapering evenly to 
the obtuse apex, the length being about 3;/55 inch. 
The smallest papilliform growths from the intine are conspicu- 
ous on the surface, as the superficies of the grain is examined, but 
their diameter at their exit through the extine is only ;,';> inch, 
their height measuring ;;5, inch. The pollen grains themselves 
are spherical, measuring about 5}, inch in diameter. 
For the pleasure of examining the pollen of Jacquemontia, as 
well as that of Ipomcea sagittata, I am indebted to a generous corres- 
pondent in Mobile, Ala., Mr. W. S. McNeill, the well known student 
of the Diatomacez. 
