98 Transactions. 



In L. volubile the hyphae of the fungus pass into the basal cell of the 

 rhizoids, penetrate the outer wall near the base of the rhizoid proper, and 

 so come into contact with the humus in which the prothallium grows. 



In order to examine the fungus and trace its distribution, hand-cut 

 sections were soaked in caustic potash, washed in water, and stained with 

 iodine. This treatment caused the. fungus filaments to stain a red-brown 

 colour. In different cells the fungus presented quite, a different appearance. 

 In many cells, particularly those of layer (b) (fig. 4), the hyphae formed a 

 dense coil (fig. 5) or else a number of parallel threads. In others, again, 

 especially in the basal cells of the rhizoids, it formed several thick densely 

 staining threads. In other cells are seen what Lang terms " multinucleate, 

 vesicles " (figs. 6, 7, 8). These arise by the swelling-up of the hypha, and 

 at first each contains only one nucleus (fig. 6), which stains deeply, though 

 the vesicles themselves stain lightly. Several of these " multinucleate 

 vesicles " may be present in a single cell. In other cells were dark spore-like, 

 bodies, but it was impossible to trace how they arose. Possibly they arose 

 by the bursting of multinucleate vesicles. 



Reproductive Organs. 



In L. volubile the antheridia and archegonia are formed on the same 

 prothallium, and are both confined to the upper surface. Antheridia are 

 usually first formed, the youngest being nearest to the meristematic zone ; 

 but as soon as a number have been formed archegonia begin to form nearest 

 the growing-zone. Thus the central part of the upper surface of the pro- 

 thallium often bears spent antheridia, while the marginal ridge bears mature, 

 archegonia. Apparently in some cases a fresh zone of antheridia may be 

 formed, since on one of the prothallia which bore the foot of a young sporo- 

 phyte all stages of antheridia from the single cell to the spent antheridium 

 were found. 



The antheridium arises from a single surface cell which is distinguished 

 by its large nucleus. This cell divides into two, the outer of which forms the 

 cover cells by anticlinal divisions only ; while the inner divides repeatedly 

 to form small-celled tissue, the spermatazoid mother cells. From the cells 

 of the prothallium bordering on the mass of spermatazoid mother cells, 

 narrow tabular cells are cut off so that the mature antheridium is surrounded 

 by these cells. At first the cover cells are flush with the surface, but later 

 they project a little in most cases. In one case an antheridium was found 

 which appeared to project beyond the prothallium for fully half its length. 

 Further examination, however, showed that only the six apical cells of the 

 antheridium were cover cells, those lower down which are divided by peri- 

 clinal walls being prothallial cells. 



The archegonia also arise from a single superficial cell which contains a 

 large deeply staining nucleus. This cell divides into a row of three cells, 

 the outer of which forms the neck cells, the inner gives rise to the ovum, and 

 the middle cell to the neck canal cells. The outer divides by a perpendicular 

 wall, and these cells by further divisions form the neck, which in the mature 

 archegonium projects considerably below the surface. A cross-section shows 

 that the neck consists of four rows of cells. The mother cell of the neck 

 canal cells divides. In a nearly mature archegonium only a single division 

 wall had been formed in the neck canal mother cell ; but nuclear division 

 had^continued so that in the outer cell there were six nuclei arranged in 

 pairs, each pair surrounded by a little cytoplasm. A still later stage shows 

 the ovum below containing a large deeply staining nucleus with a single 



