126 



Scientific Proceedings, Roijal Dublin Society. 



formed of a vertical row of superposed compartments. It may be a 

 synangium of united sporangia, comparable to one-half of a small vascular 

 " sporangiferous spike," sucli as that of OpMoglossum (fig. 2). I have made a 

 number of drawings of the surface features of different sporangia, 

 and have also liad photographs taken of magnified sporangia. 

 It is desirable to exclude as far as possible the personal equa- 

 tion in the interpretation of the structure of the Archseopteris 

 sporangium, and to let tlie evidence speak for itself, in the 

 photographs. It is not easy to dissect out an intact sporangium 

 from the rock ; but occasionally it is possible to get a fairly 

 complete one. Such is that in PL V., figs. 2 and 3, in which 

 the transverse segmentation is unmistakable. Fig. 3 is a drawing 

 of the same sporangium magnified forty-five times. The speci- 

 men was treated with eau de javelle for several months before 

 being separated out, and was subsequently, wlien isolated, after being 

 pliotograplied, treated with Schulze's macerating liquid and ammonia, and 

 again photographed. It became mucli clearer at one 

 end, and at the other the septation was recognizable by 

 reflected, but not by transmitted light. This septation 

 is too constant, regular and deep-seated to be dismissed 

 as artificial. It is, of course, impossible to say how 

 the assumed partitions arose — i.e., whether the spore- 

 capsule is a synangium, formed of fused sporangia, or 

 a single sporangium made multilocular by the sterili- 

 zation of plates of potential sporogenous tissue. The 

 compartments may open independently by their own 

 transverse pores, or the longitudinal grooves mentioned 

 may be indicators of longitudinal deliisceuce. It is thus 

 possible that the locules ojjen in common longitudinally. 

 The partitions are sometimes more or less irregular. 

 This inconstancy in direction in this primitive fossil is 

 not surprising. There is considerable variety in the 

 direction of the slit of the sporangium in, e.g., Botry- 

 chium. The vascularity of the stalk is a sure sign 



"- -'' that the s]K)raugium has a long past, and that it was 



Fig. 3. a body of fundamental physiological importance even 



in the Devonian epoch. 



Archseopteris has been described as a tree-fern, as one of tlie Hymeno- 



' From Eugler's " Die Flanzenfamilieu." 



