30 
about the same thickness as the outer, but with a more distinct double 
contour (Mertens, 1892). At two opposite points, usually corres- 
ponding to the poles of the egg, the inner membrane has a small marn- 
millated j)rojection^ often not apparent. To each of these projections 
are attached a number of clear hyaline fibers^ resembling elastic fibers 
in appearance, which pass outward through the intermediate substance 
toward the outer membrane. Whether there is any constancy in the 
number of these filaments is not known. Mertens (1892) in observing 
an egg turned on end, saw at one pole as maiw as 8, converging like 
spokes in a wheel and attaching to the papilla of the inner membrane. 
Fig. 37. — Eggs of H. nana from mouse. Enlarged. (After Krabbe, 1865, pi. 7, fig. 108.) 
Fig. 38.— Egg of H. nana from man. Enlarged. (After Bizzozero, 1889a, pi. 4, fig. g'.) 
Fig. 39. — Eggs of II. nana from rat. Enlarged. (After Grass! & Rovelll, 1892a, pi. 3, figs. 1 and 2.) 
Fig. 40.— Egg of II. nana. Enlarged. (After Mertens, 1892, fig. 1.) 
Fig. 41. — Egg of II. nana from man. Enlarged. (After Linstow, 1896a, fig, iv.l 
Fig. 42.— Egg of H. nana from rat. Enlarged. (After Linstow, 1896a. fig. 4.) 
Beginning at the papillie the filaments pursue an irregular, winding 
and convoluted course, gradually becoming more tenuous, but, so 
far as may be observed, do not branch, and end finally in the j^eri- 
pheral portion of the intermediate substance directh" underneath the 
outer membrane. Two layers of slightly difierent appearance may 
often be distinguished in this intermediate substance, an inner portion 
which is clear and homogeneous, free from fibers except where it is 
penetrated by them in the two polar regions, and a thicker outer por- 
tion which is granular and in which the distal ends of the fibers int#r- 
lace, forming an irregular meshwork. For a great part of their course 
