Sands—Spore Formation in Microsphaera Alni. 745 
upper end of the spore in shrunken material, has been pointed 
out by Harper (13). This shrinkage of the upper end of the 
spore often occurs long before the spore-plasm is delimited 
and when there is no sign of a hyaline zone or of any othei 
differentiation in the cytoplasm to indicate the position of the 
future spore membrane. The cytoplasm facing the cleft made 
by the shrinkage is ragged and without a definite boundary, 
while the end of the spore is smoothly rounded off and has a 
continuous outline. 
The fusion of the rays progresses slowlv toward the interior 
of the ascus, following the longer fibers which have grown past 
the nucleus and are now converging toward a point opposite 
the central body and some distance below the nucleus. These 
advance fibers mark the path of the plasma membrane, passing 
into its composition as the fusion progresses. These stages 
look like Faull’s figures of the hyaline zone, but the fibers al¬ 
ways stain blue and do not increase in thickness. 
The cleft formed by the shrinkage either of the spore or of 
the surrounding epiplasm narrows from the center outward 
along the plasma membrane which covers the upper part of 
the spore-plasm. When the epiplasm is shrunken, it is thick¬ 
ened at its inner edge simulating a membrane, so that at first 
glance it suggests two plasma membranes developing from the 
center outward, such as Faull describes. Closer scrutiny, 
however, proves the absence of a membrane on the surface of 
the epiplasm facing the opening. This cleft, of course, may 
almost surround the spore, or it may only cap it, according to 
the stage of development of the plasma membrane of the spore. 
The kinoplasmic fibers finally meet at a point below the nu¬ 
cleus, having cut through the cytoplasm so as exactly to enclose 
an ellipsoidal mass of protoplasm, in the upper end of which 
lies the nucleus, still attached by its center to the new 
plasma membrane (Figs. 13, 14). The beak has been greatly 
elongated, but is still traversed by chromatin strands con¬ 
nected to the centrosome. Sometimes the nucleus is swung 
to one side and lies against the plasma membrane of the spore 
(Fig- 14)- 
After the fibers have completely fused, so that the spore- 
