1 3° 
Steil. — Apogamy in Nephrodium hirtipes , Hk. 
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(1908 b): Sporogenesis in Nephrodium. Ibid., 1-30. 
— - 7 : — (1908 c): Apogamy in Nephrodium. Ibid., 289-319. 
EXPLANATION OF PLATES V-VII. 
Illustrating Dr. W. N. Steil’s paper on Apogamy in Nephrodium hirtipes. 
The photo-micrographs on Plate V represent different magnifications. The young sporophytes 
from which photographs 13-21 and 23 were made are magnified about 2J diameters. The figures on 
Plates VI and VII, excepting 29, 30, and 31, were drawn with a Zeiss compensating ocular No. 12, 
and apochromatic objective, 2 mm. N. A. 1.30, at table level with the aid of a camera lmrda. With 
a tube elongation of 142 mm. a magnification of about 2,150 diameters was obtained. Figs. 29, 30, 
and 31 represent a magnification of about 1,250. 
PLATE V. 
Fig. 1. A dorsal view of a young prothallium. 
Fig. 2. A dorsal view of a young prothallium just before the embryo becomes visible. 
Fig. 3. An older prothallium, viewed from the ventral side. The small dark region posterior 
to the apical notch represents the outer cells belonging to the young embryo. 
Fig. 4. A dorsal view of a highly magnified portion of a prothallium. The embryo is visible as 
a compact area in the paler portion. 
Fig. 5. A dorsal view of an older embryo. 
