APPENDIX 641 



Bruchmann also found that in some species, e.g., S. Martensii, S. 

 spinulosa, no diaphragm is developed, but that there is a gradual 

 transition from the small-celled archegonial tissue at the apex to the 

 larger-celled tissue of the basal region. In S. GaleoUei the cells are 

 arranged in concentric layers, but there is no diaphragm. 



P. 518. Bruchmann's recent studies on the embryo show much 

 variation. In S. denticulata the first or basal wall divides the embryo 

 into a hypobasal and epibasal cell, as in 5. Martensii, but from the 

 former is developed not only the multicellular suspensor, but also the 

 foot and later the first rhizophore. In S. ruhricaulis the foot is also 

 of hypobasal origin, but the suspensor is very short. 



P. 520. Bruchmann figures a prothallium of S. Kraussiana, 

 showing rhizoids. These are, however, much less conspicuous than 

 in some other species, e.g., S. GaleoUei, where there are large promi- 

 nences with a bunch of long rhizoids at the outer angles of the pro- 

 thallium. He states that rhizoids occurred in all the species examined. 



S. GaleoUei shows a marked difference. A membrane is formed 

 about the fertilised egg, which then contracts and forms another 

 membrane, after which it divides into two cells. The young embryo 

 thus lies within a membrane, which now elongates and carries the 

 young embryo down into the endosperm, part of which has become 

 disintegrated. In a later paper (10) he states that this is also the 

 condition in S. Kraussiana. The elongated "suspensor," therefore, 

 figured in the text (Fig. 298, A. sus.) is this tube which bears within 

 it the young embryo shown in Fig. 298, F. 



In two species, S. spinulosa and S. ruhricaulis, Bruchmann found 

 embryos developed parthenogenetically. 



P. 524. A detailed study of the strobilus of Selaginella has been 

 made by Sykes (4) and Mitchell (i). From these investigations it 

 appears that there is a good deal of variation in several respects in 

 different species. The sporophyll itself may be quite simple, or it 

 may be provided with a dorsal flap, which acts as a protection for the 

 sporangium belonging to the next older sporophyll. This is especially 

 marked in 5. pumila (Sykes and Stiles (4), p. 524). 



The distribution of the two sorts of sporangia, also, shows much 

 variation (Mitchell (i)). In S. spinosa, S. rupestris, S. Helvetica, 

 among others, are found several basal macrosporangia, followed by 

 numerous microsporangia. In S. atroviridis, S. gracilis, and others, 

 the cones are wholly macrosporangiate or microsporangiate. In 

 another category, e.g., S. Martensii, S. caulescens, etc., there is an 

 indiscriminate mingling of macrosporangia and microsporangia. 

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