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PROFESSOR A. AN ST RUT HER LAWSON ON 
the young archegouia project like short tubes for a considerable distance beyond the surface of the prothallus. 
Many cells— even from the surface view — show the presence of the endophytic fungus, x 55. 
Fig. 3. This figure represents a transverse section of the prothallus. It will he seen that the prothallus 
is more or less cylindrical, with a definite layer of superficial or epidermal cells from which the rhizoids are 
given off. Nuclei and protoplasm are present in the majority of the cells, hut many of them are infected 
with an endophytic fungus, x 75. 
Fig. 4. This represents a section of an older region' of the prothallus. It will be observed that the 
superficial cells are the only ones not infected by the fungus. Many of the cells have lost their nuclei and 
cytoplasm, the entire contents being replaced In' the fungus. x 75. 
Fig. 5. A representation of a few superficial cells of the prothallus with rhizoids. A study of these 
rhizoids suggests a possible source of infection. It would seem from a study of these older rhizoids that the 
fungus enters the prothallus by way of the rhizoids. In the figure the fungus is shown traversing the entire 
length of the rhizoid and entering the cells of the prothallus. These infected rhizoids, showing the great 
length of the fungal hyphse, make it easy to prove the non-septate nature of the latter. x 290. 
Fig. 6. Here we have a representation to show the effect of the fungus on the infected cells. The figure 
was drawn from cells near the very centre of the prothallus. It will be seen that in many cases the nucleus 
disintegrates and eventually disappears. The cell cavities become almost filled with the fungal hyphse, and 
the various stages in the degeneration of the nuclei are indicated, x 290. 
Fig. 7. This figure represents a section of a very young antheridium. The wall consists of a few 
superficial cells covering a large inner cell whose nucleus has just undergone a division. The two nuclei thus, 
formed are very large, and are very conspicuous as compared with the nuclei in the wall cells. The cytoplasm 
of the inner antheridial cell is dense and granular. x 290. 
Fig. 8. We have here represented a section of an antheridium slightly older than that shown in fig. 7. 
The wall cells have increased in number, and the inner cells have undergone mitosis, and cell w’alls have 
been formed between them. There are eight inner cells shown in the section. The dense granular cyto- 
plasm and large deeply staining nuclei make these cells stand out in sharp contrast to the ordinary vegetative- 
cells of the prothallus. The young antheridium projects as a spherical protuberance from the prothallus. 
x 290. 
Fig. 9. A representation of an antheridium at an older stage in its development than that shown in 
fig. 8. It will be observed that the inner cells have undergone repeated mitoses, and there is now a large 
central mass of sperm mother-cells or spermatocytes. The wall cells have also enlarged, and the young 
antheridium has increased considerably in size, x 290. 
Fig. 10. This represents a section of an antheridium further developed than that shown in fig. 9. The 
size has still further increased, and the spermatocytes, by reason of the increased space in the interior, are 
less crowded. They even appear to be separating from one another, x 290. 
Fig. 11. This figure represents a tangential section of a nearly mature antheridium. It will be seen 
that the nuclei of the spermatocytes have undergone a change. They appear now as dense crescent-shaped 
or slightly coiled bodies that stain very deeply with nuclear stains. These are the immature spermatozoids. 
x 290. 
Fig. 12. We have represented here a mature antheridium, as seen from the surface. Only the- 
wall cells are represented, and their arrangement in the form of an almost spherical body is very 
characteristic. x 290. 
Fig. 13. This figure represents a longitudinal median section of a mature archegonium. It will be seen 
that the egg cell lies below the surface of the prothallus, and the neck forms a short straight tube projecting 
at right angles to the surface. The neck consists of at least four tiers of cells, x 290- 
Fig. 14. This figure represents a surface view of three archegonia. It shows quite clearly that the neck 
of the archegonium which projects above the surface of the prothallus consists of four cell rows, and that 
the latter enclosed a comparatively narrow, channel occupied by the neck canal cell. This is a very 
characteristic appearance of the archegonia when viewed from above. x 290. 
Fig. 15. A representation of a longitudinal section of a mature archegonium. It will be observed that 
the main portion of the neck, consisting of the three upper tiers, has been torn away, leaving behind only 
the lower tier with the egg cell in the venter. x 290. 
