740 MINNESOTA BOTANICAL STUDIES. 
5. Plant ‘*B” of text; the midrib is more distinct and the two op- 
posite growing points of the first pair of pinne may be seen just be- 
low the junction of lamina with stipe. 
ee, IEW 0. 
Plant ‘*C” of text. The plant is shown a little more than one- 
third the natural size. It presents the loosely arranged pinnz charac- 
teristic of young plants and as shown in Ruprecht’s plate. The lower 
pinne are perforated by marine animals and are the ones in which the 
reserve material is the most abundant. The mid-lamina alone shows 
a midrib. 
\eiorie IOIDG 
Plant ‘‘D” of text. The size is indicated by the hat placed in the 
field of view. It is about one-tenth natural size and was photographed 
on the shore a few moments after collection. It is somewhat fore- 
shortened, being between three and four meters in length. The cen- 
tral lamina is shown in line with the stipe. 
learns JUKE 
Pinna-region of full-grown specimen, one-half natural size. The 
very much crowded position of pinne in old plants is indicated in this 
plate. Below the pinne may be seen scars left by pinnz of previous 
seasons. 
PLATE 2X1, 
Cross sections through the stipe, natural size. The lower figure is 
taken near the base of the stipe, while the upper is cut just below the 
region of pinne. The great difference in the extent of the pith and 
in its shape, in the two sections, is noticeable. The characteristic 
rings of growth are apparent in both figures. 
Plates LVII. to LXI. are from photographs made under the direc- 
tion of the author, by Mr. C. J. Hibbard, Photographer of the De- 
partment of Botany in the University of Minnesota. 
PrarE Toxdi: 
The anatomical detail of Prerygophora. 
1. Cross section through secondary cortex of stipe, showing rings 
of growth (x 50). 
2. Cross section through stipe, showing secondary cortex above and 
primary cortex below (xX 50). 
3. Longitudinal section through secondary cortex showing flatten- 
ing of cells towards the right. This would appear as a ring in the 
cross section ( X 50). 
