PROCEEDINGS OF THE CANADIAN INSTITUTE. 9 



are situated. The archegonia are found on the declivities which slope away from 

 the antheridial ridge. 



As might be expected, the younger sexual organs are found nearer the growing 

 point than those of greater age. 



A cross section of the prothallium reveals to the naked eye the fact that the 

 lower part of the gametophyte is composed of tissue which is yellowish in colour, 

 and from which a thick oil exudes, even when the plant has been lying in ninety 

 per cent, alcohol for months. The upper portion of the prothallium tissue, upon 

 which the generative organs are situated, is white in colour and free from oil. A 

 long section of the prothallium shows the same distribution of yellow oil-bearing 

 and white oil free tissue as the cross section, but demonstrates that the oil-bearing 

 stratum is both absolutely and relatively much thicker in the older parts of the plant. 



Microscopic examination shows that the oleiferous tissue has its cells occupied 

 by an endophytic fungus and a very abundant protoplasm. 



The fungus, so far as it has yet been studied, seems to be a sterile Pythium. 

 possibly the same as that found by Treub, Goebel and others in the prothallium of 

 species of Lycopodium. The writer hopes to study the fungus more closely in a 

 living condition during the next period of vegetation. The fungus filaments can be 

 seen passing from the prothallium to the outside medium by way of the root hairs. 



The antheridia, as has been already stated, occur in numbers on a ridge running^ 

 lengthwise on the upper surface of the prothallium. The young antheridia originate 

 behind the growing point from a single superficial cell. This divides transversely 

 the outer half, giving rise to the outer antheridial wall and the inner half by: 

 repeated simultaneous divisions to a large number of spermatocytes. The fully- 

 developed antheridium is largely embedded in the antheridial ridge, and projects 

 only slightly above its surface. The formation of the spermatozoids has not yet 

 been carefully studied, but seems to resemble closely that described in the Marat- 

 tiaceae and Equisetaceae. 



The spermatozoids are unusually large in size, but otherwise resemble the 

 ordinary fern type, and consequently dififer from the biciliate, moss-like sper- 

 matozoids of the Lycopodiales. 



The archegonia are confined to the sloping sides of the upper surface of the- 

 prothallium. Unlike the antheridia, young archegonia, although most abundant 

 near the grow'ing point, may ; be formed on almost any part of the archegonia- 

 bearing surface. The archegonium mother cell is superficial, and is distinguished' 

 from its neighbours by a larger nucleus and a more abundant protoplasm. It first 

 divides transversely into a shallow outer cell and a deeper inner cell. The inner- 

 cell divides again, and as a result the young archegonium consists of three cells. 

 The most external of these, by subsequent divisions, gives rise to the neck of the 

 archegonium. The internal cell is the basal cell. It also divides into a plate of cells 

 sometimes composed of two layers and distinguished by their richly protoplasmic 

 contents. The middle cell of the young archegonium series gives rise by divisiot> 

 to the neck canal cell and the ventral cell. The former becomes binucleate, but 

 never divides into two cells. The latter, just before the maturation of the arche- 

 gonium, divides into the egg-cell and the ventral canal cell. The ventral canal cell 

 is broad, like that of the Marattiacea?. 



In the ripe archegonium the nuclei of the cells of the upper stories of the 

 archegonium neck become chromatolysed. I do not know yet whether this feature 

 is peculiar to Botrychium. 



The fully-developed archegonium is sunk into the prothallium, and only the 

 neck projects above its surface. The cervical cells are in four rows as in the other 

 Pteridophyta and the terminal ones spring apart when the egg is ripe. 



Speimatozoids are frequently found in contact with the egg. After fertilization 

 the egg grows to many times its original size, and the reduced protoplasm contains 

 a large hydroplastid. 



