Thorn — Fertilization in Aspidium a7id Adiantum. 305 



about the lowest point in the funnel b. Outside the nucleus 

 we find a coil and a half beginning at a and passing through 

 the nuclear membrane at e. This part contains no nuclear 

 material and continues without chromatin through the nuclear 

 membrane as far inside the nucleus as c, where it passes 

 under a turn of the nucleus. That is, the part from a to c 

 contains no nucleus. Passing under the coil of the nucleus 

 at c, it reappears on the other side as nuclear. The connec- 

 tion between the two could not be seen, but the fact that they 

 were connected is beyond question. A glance at the part 

 from a to c and a comparison with the nuclear portion show 

 that the two are almost of equal length and similar in 

 diameter. So we have here in the same figure both nucleus 

 and its cytoplasmic envelope and both perfectly recognizable. 

 Figures 17 and 18 are two sections of another ^^^ in the 

 process of fertilization. In this ^g^^ the depression lay in 

 the side of the cell in the section below the one shown in 

 figure 17. Figure 18a is intended to show the nucleus of 

 this egg viewed from the mouth of the archegonium, leaving 

 out entirely the details of form. The nucleus is very large, 

 quite irregular in outline, with a marked depression in the 

 side, turned toward the mouth of the archegonium. The 

 colorless coils c, c', of the spermatozoid lie in this depression 

 just below the plane of the section in figure 17, viewed from 

 above in figure 18a. The point (?, figure 18a, shows the 

 end of the nuclear portion of the spermatozoid just inside 

 the nucleus of the esfg still connectins: with the colorless 

 portion outside the nucleus. The point of entrance lies 

 behind the nucleolus e in figure 17. Once inside, the entire 

 sperm-nucleus may be followed through the two sections. 

 It was reconstructed in wire and drawn to scale in fiojure 18a. 

 Careful examination of the end d in figure 17, which is con- 

 tinued in the portion f of figure 18, shows that in this case the 

 slender pointed end was the last to enter the nucleus of the ^gg. 

 The same fact is indicated in figures 10, 11 and 13, but is best 

 demonstrated in this figure where both blunt and pointed ends 

 may be found in the same section. This spermatozoid seems 

 therefore to have coiled itself in the depression in the surface 

 of the cell. It then broke through the cytoplasm into the egg 



