284 Shaw . — The Fertilization of Qnoclea. 
EXPLANATION OF FIGURES IN PLATE XIX. 
Illustrating Mr. Shaw’s paper on Onoclea. 
Fig. 1 was drawn with a Leitz objective No. 7, and a Leitz drawing-ocular ; all 
the others were drawn with a Zeiss apochromatic 2-0 mm objective, apert. 1*40; 
Figs. 5 and 12 with a Zeiss compensation ocular No. 12 ; the others with a Zeiss 
compensation ocular No. 8. For sketching the figures (except Fig. 1) the prism 
section of a Leitz 45 0 drawing-ocular was screwed to the Zeiss compensation-ocular 
in place of the upper diaphragm holder. 
Magnification determined with a stage micrometer : — Fig. 1 x 500 ; Fig. 5 
X 2,000; all others x 1,200. 
All figures are from sections 10 ju thick. 
The arrow indicates the direction of the growing point of the prothallium. 
The time given is that which elapsed between the entrance of the first sperma- 
tozoids and the fixing of the prothallium. 
Onoclea sensibilis. 
Fig. 1. One per cent, chromic acid : alum-cochineal and Bismark brown. 
Vertical section through an open archegonium probably within ten minutes after 
the entrance of the first spermatozoid. One unchanged spermatozoid is inside 
the egg-nucleus. Parts of two coils of this spermatozoid were cut off, and appear 
in the next section of the series. 
Fig. 2. One per cent, chromic acid : alum-cochineal. Thirty minutes. Vertical 
section of the venter of an archegonium containing spermatozoids, and the collapsed 
egg with a spermatozoid within the nucleus. The canal of this archegonium is 
almost closed. Two spermatozoids in the section were not drawn. 
Fig. 3. One per cent, chromic acid: alum-cochineal. Three hours. Nearly 
vertical section of the egg. The outside spermatozoids are forced against the 
venter wall by the expanding egg. Portions of the egg-nucleus, one containing 
a nucleolus, are in each of the adjoining sections of the series. 
Fig. 4. One per cent, chromic acid : safranin and orange G. Twenty-four hours. 
Vertical section of an egg in which fertilization is not much in advance of the 
preceding case. 
Fig. 5. Half per cent, chromic acid : Delafield’s haematoxylin. Eighteen hours. 
Spermatozoid caught in the slime outside an archegonium showing the kino- 
plasmic band extending as a wing along the forward side of the two anterior coils 
of the corkscrew-like nucleus. 
Fig. 6. One per cent, chromic acid : safranin, gentian-violet, and orange G. 
Twenty-four hours. Two vertical sections of an egg. The male chromatin 
partly distributed in the egg-nucleus. The lightly shaded spermatozoid is in 
a lower focus. 
