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stome. *Philibert in his masterly treatment of the structure of the peri- 

 stome calls attention to this correlation of symmetric erect capsule with 

 a degenerate peristome but gave no explanation for the very evident 

 facts. In this connection he mentions Anojnodon viticulosus, Habrodoii 

 Notarisii and Pylaisia polyantha, calling attention not so much to the 

 inner peristome as to the disappearance of the fine horizontal lines which 

 mark the lower outer lamellae of the typical hypnaceous peristome. Most 

 striking illustrations of the correlation of the erect capsule with an im- 

 perfect developed inner peristome are furnished by Brachythecium acu- 

 inmatum and its allies, Plagiothecium latebricolor , and the genera Pylaisia, 

 Entodon, Orthothecitim, Isothecium and Homalotheciu7n. This also explains 

 why Thuidium and its allies have a perfectly developed inner peristome while 

 most of the Leskeacese, having erect capsules, have also imperfectly de- 

 veloped peristomes. I am inclined to think that this principle, modified by 

 an annual habit of growth, or a very low minute growth, or both, will ex- 

 plain the lack, partial or complete, of a peristome in Physcomitriimi, Pottia, 

 Pleuridiiim, Mollia viridula, and other species of a similar habit and struc- 

 ture. It will also explain the degenerate condition of the peristome in Or- 

 thotrichuvi and its allies. However, it seems very probable that we not yet 

 fully understand why mosses like Pleuridiuin do not seek the assistance of 

 a peristome in their spore distribution and I would suggest that this ques- 

 tion offers a fascinating field for investigation. 



To return to Georgia ; its capsules are erect and its four teeth well sepa- 

 rated when dry as seen in Plate 5, Fig. 3. Dip one of the dry capsules in 

 warm water for a moment and see the peristome close like a tiny vise, giv- 

 ing an almost comical impression of grim determination. (PI, 5, Fig. 4). 



In Polytrichujn the teeth are 64 in number and of themselves are usu- 

 ally so short that they would have little effect upon spore distribution, but they 

 are all attached by their tips to the expanded membranous upper end of the 

 columella, forming a most effective and ingenious pepperbox, entirely auto- 

 matic in action. When the weather is dry the teeth become shrunken in 

 width and strongly incurved, the coUumella also shrinks, pulling the ends of 

 the teeth inwards (PI. 5, Fig. 2). This leaves ample room for the spores to 

 be shaken through the openings between the teeth. The columella shrinks 

 more at the margin than in the central portion, causing it to assume the 

 shape of a pieplate. This upturned margin of the columella also enables the 

 teeth to remain attached to its edge in their changed position. In species of 

 this family with more nearly erect capsules the teeth are longer and often 

 fewer in number, making the escape of the spores easier. 



If you take a capsule in the condition represented in Fig. 2 and place it 

 in warm water for a few minutes it will assume the appearance shown in 

 Fig. I and no spore can be shaken out, although a careful examination of the 

 contents of the capsule will show that the spores are not wetted, as when 

 mounted in water they are still surrounded by an envelope of air. 



The pepperbox is closed, but how ? Kerner von Marilaunf states that 



*Rev. Bryologique, ii; 51, 1887. tNat. Hist, plants, 2; 814. 



