14 GEAF ZU SOLMS-LAUBACH— MONOGRAPH OF THE ACETABULAEIEiE. 



exactly true to nature. The hair-scars also have escaped his notice. The very character- 

 istic lime -incrustation of JELalicoryne does not appear to have been taken into account by 

 Agardh, who at all events does not describe it. 



If we examine the surface of the axial tube of the young part of a plant, the whole external 

 surface of the membrane will be seen to be covered with round scale-like groups of 

 minute needle-shaped crystals of calcium carbonate, between which there remain small 

 interstices almost free from lime. These scales subsequently increase greatly in size, and are 

 easily broken out with a needle ; they become united into a continuous crust, though the 

 interstices are much less strongly calcified. If the carbonate be dissolved with acetic 

 acid, the thick membrane is left clear as glass, acd there are to be seen numerous oxalate 

 crystals, often densely occurring, firmly attached to its inner surface. Transverse sections 

 show that the thick, strongly refractive, clearly stratified membrane remains wholly free 

 from lime, and that the incrustation is only in a slimy coating developed on the outer- 

 most margin ; its unequal distribution may have given rise to the scaly lime-formation. 

 On decalcifying such sections one sees the slimy substratum of the incrustation always 

 appear in little hillocks at the places corresponding to the scales. 



The whorl rays are the same in this respect, but in them the calcification is much less 

 and inconsiderable. 



The spores of Halicoryne (Plate IV. figs. 3, 7) are in structure similar to those of 

 Chalmasia ; they are, however, in the two species so far different that while in Halicoryne 

 Wrightii they fill the sporangium with white globules in great numbers, in R. spicata they 

 are present in much fewer numbers and are united in an irregularly formed aggregation 

 like a small roundish oval stone, in which only after decalcification are the single 

 elements, polygonal from mutual pressure, to be clearly recognized. 



The single spore of R, Wrightii is almost globular, and is distinguished, as already 

 mentioned, by the complicated structure of its extremely thick cell-membrane ; to what 

 has been said (under Chalmasia) with reference to the lid and its insertion there is 

 nothing to be added. If the spores be embedded in gum and the sections so obtained 

 be examined, the whole membrane will be seen to consist of three different layers. The 

 greatest of these is the middle one, which is the seat of calcification. It exhibits a 

 peculiar striation in the direction of the radii, which causes the delicate stratification, 

 which is also present, to be scarcely apparent, if at all, though it is somewhat more 

 distinct in H. spicata. The striation depends apparently on differences of density in the 

 substance ; the minute lime-granules of the incrustation, disposed in radial rows, follow it, 

 and without doubt they are situated in the less dense layers, and they appear clearly 

 during the first effects of dilute acetic acid or after treatment with chloriodide of zinc. 

 After their solution the striation is stiU clearly apparent, but later it becomes less 

 distinct from the swelling up. At the outer and inner margins of this layer of the 

 membrane there is a denser seam showing the radial striation, but either free from or 

 almost destitute of lime, which appears very sharply defined at the commencement of 

 staining with chloriodide of zinc, because the colour-reaction begins in it later than in 

 the remaining weaker part of the middle layer. The cellulose reaction is easily obtained, as 

 de Bary has stated for Acetabular ia mediterranea, and mere treatment with iodine is 



