l8g6-97.] THE GAMETOPHYTE OF BOTRYCHIUM VIRGINIANUM. 277 



and re-staining with the reagents employed by Belajeff. The writer 

 hopes to secure more young prothallia in the coming summer, in which 

 event it will be possible to come to a decision on this important point. 



The fully developed antherozoid forms a spiral of one and a-half turns 

 and has the structure usual in the Filicinece. The cilia come off from 

 the attenuated, anterior end of the spiral. I could not decide, from the 

 preserved examples which were the only ones I had the opportunity of 

 examining under high magnification, the exact length of the ciliary 

 region. The antherozoids, like those of Ophioglossum pednnculosuin 

 described by Mettenius'^, escape from the mother-cells while still within 

 the antheridiuui. They swim about freely in its cavity, figure 28, a and 

 b: sometimes still retaining their protoplasmic vesicles and in other 

 instances being already freed from them, figure 27, e' and e- . The 

 spermatozoids make their way out by means of an aperture formed by 

 the disappearance of two superimposed cells of the outer wall of the 

 antheridinm. They do not escape all at once, as is quite generally the 

 case, but seem to be voided in several swarms, at intervals, under undis- 

 covered conditions. The cavity of the antheridiuni is filled with a thin 

 gelatinous matrix, resulting, probably, from the disintegration of the 

 spermatocytic walls, figure 28, a and b. 



VII. 



As has already been stated, the arcJiegonia originate on the flanks of 

 the median ridge of the prothallia, figure 15, j'. The youngest stage of 

 the arxhegonium is a single, richly protoplasmic, superficial cell, which, 

 as in the antheridiuDi, divides subsequently into an outer shallow cell 

 and an inner deeper one, figure 29. The former gives rise to the neck 

 of the archegonmni, and the latter to its axial row of cells. The next 

 stage is the horizontal division of the inner rudiment which separates 

 from it the large basal cell, figure 30. The superficial rudiment sub- 

 sequently begins to divide, first, by anticlinal walls, figure 31 ; and then 

 by periclinal ones, figure 32 ; thus forming the neck. The richly 

 protoplasmic basal cell divides, figure 32 , and then the upper axial cell 

 undergoes a division, which results in the formation of the cervical 

 canal-cell and the ventral cell; figure i-}, and figure 34. In the latter 

 figure is seen a paraphysis, a, which is in reality, only one of the multi- 

 cellular hairs common over the whole surface of the younger parts of 

 the prothallium. In figure 35, the nucleus of the cervical canal-cell has 

 divided, and as may be seen in the next figure 36, the nuclear division 



18. Op. Cit. 



