Fertilization in Finns Strobus. 
477 
Fig. 89. The framework of the primary nucleolus from a mature egg-nucleus, 
x 1 200. This nucleolus has remained of a light greenish-yellow colour after treat- 
ment with Flemming’s triple stain. 
Fig. 90. The primary nucleolus of a mature egg-nucleus. This nucleolus 
shows a weak reaction towards dyes, and apparently has 'hn outer limiting 
membrane, x 1200. 
PLATE XXIV. 
Figs. 34-35. Later stages in the downward movement and growth of the egg- 
nucleus. x 540. 
Fig. 36. Mature egg-nucleus, x 540. 
Fig- 37 , a-g. Portions of the reticulum from different mature egg-nuclei, 
showing the variations which may exist in the structure of this nucleus, x 1200. 
Fig. 38. The upper part of an archegonium, showing cavity formed in the 
cytoplasm just prior to fertilization, x 160. 
Fig. 39. The upper part of an archegonium just after the entrance into the egg 
of the elements from the pollen-tube, x 160. 
Fig. 40. A slightly later stage. The cytoplasm of the sperm-cell has already 
fused with the cytoplasm of the egg. x 160. 
Fig. 41. An entire archegonium showing the sexual nuclei in contact, and, 
above them, the various elements which have come into the egg from the pollen- 
tube. X 70. 
Fig. 42. The upper part of an archegonium in the same stage as the above, 
x 160. 
Fig. 43. The sexual nuclei just before coming into contact. Note depression 
in egg-nucleus, x 160. 
Figs. 44-50. Various appearances presented by the conjugating nuclei. It will 
be borne in mind that these figures are so placed that the major axis of the 
archegonia in which they occur would lie parallel with the longer axis of the half 
plate, x 160. 
Fig. 50 b. Another section through the egg-nucleus shown in number 50. There 
is a greater difference in the size of the conjugating nuclei than would appear in 
figure 50. x 160. 
Fig. 51. An early prophase in the first division following fecundation, x 540. 
Fig. 52. A slightly later stage. The cytoplasm caught between the two nuclei 
has collected into spherical masses, x 540. 
Fig. 53. A still later stage in the formation of the two chromatic spirems. 
x 540- 
Fig. 54. A still later stage in which the paternal chromatic spirem has taken up 
a position near the maternal spirem, and a few delicate achromatic threads have 
made their appearance in the neighbourhood of these spirems. The nuclear 
membranes are still present, but have broken down at several points, x 540. 
Fig- 55- A later stage. The nuclear membrane has entirely disappeared ; the 
spindle fibres have increased in number ; and the rearrangement of the achromatic, 
nuclear reticula into granular threads is very apparent, x 540. 
Figs. 56-57. More advanced stages in the formation of the spindle, x 540. 
