Gregory. — Spore- Formation in L eptospora ngia te Ferns . 457 
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EXPLANATION OF PLATE XXXI. 
Illustrating Mr. Gregory’s paper on Spore-formation in Ferns. 
The figures were drawn with a camera lucida. A Zeiss aprochromatic objective 2 mm. 1-4 N.A. 
was used for all except Figs. 32-34, which were drawn with Zeiss homog. immers. K. Compensating 
oculars 8, 12, and 18. 
Fig. 1. Onoclea sensibilis. Spore-mother-cell, showing spireme before the longitudinal fission 
has taken place, x 1000. 
Fig. 2. Asplenium Ceterach . Longitudinal fission of the spireme, x 1500. 
Fig. 3. Onoclea sensibilis. Contraction of the double spireme thread towards one side of the 
nucleus has commenced. In some places the two halves of the thread diverge from one another. 
X 1500. 
Fig. 4. Onoclea sensibilis. The contraction of the spireme with the formation of a series of 
loops, x 1000. 
