1000 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Dissemination of the Spores of Equisetum.* — According to Mr. 

 F. C. Xc'wconibo, tlicro arc throe factors iu the niechauism for the dis- 

 semination of tlic spores of Equisetum (arveuse): — (1) Tlio somewhat 

 sudden lengthening of the axis of the si)ikc immediately before ripening, 

 due to the elongation of the cells of which it is composed, by which the 

 sporangia are pushed apart. (2) The unequal contraction in length and 

 width of the strong external laj^er of cells of the sporangium-wall. In 

 this layer arc botli annular and spiral cells, (8) The action of the elaters, 

 which is twofold ; first, the ejection of the spores from the sjwrangiura, 

 which is brought about by the unequal hygroscopic properties of the two 

 layers of cells of which the ehitors are composed ; and secondly, tlio 

 facility for carriage by the wind afforded by their broad spathulato 

 extremities. 



Muscineae. 



Peristome.t — M. Philibert iu this paper concludes his observations 

 on the internal jjcristome of mosses and its variations. The Fontina- 

 lacefe, including Dicheh/ma, ought to be included among the Hypno- 

 bryaceae, while the genera CincUdotus and Scoulevia belong, on the 

 contrary, to the Aplolepidefe. In Scouleria aqiintica the jieristome is 

 remarkable ; it is composed of thirty-two large linear obtuse teeth, and 

 approaches the structure of that of Grimmia, while the peristome of 

 CincUdotus has more analogy with that of Barhida. 



After describing the Timmiaceoa in some detail, the author states that 

 this type may be considered as belonging to the Hypnobryacea), as the 

 basilar membrane and teeth preserve exactly the same structure. The 

 difference, however, becomes much more marked in the Funariaceaa, the 

 primitive plan of the peristome in this family being much the same as in 

 the Bryaceaj. The ])lates and lamelhc of the teeth are disposed in exactly 

 the same manner. The dorsal network of the internal peristome is made 

 up of a series of rectangles which are opposed to the ventral plates of 

 the teeth, and the ventral network is made up of two rows of trapezes 

 placed opjiosite to each tooth. 



The author, in conclusion, states that the simple peristome of the 

 AplolepideiE has more analogy in its structure with the internal peristome 

 of the Diplolepideas than with their external peristome. In order to ex- 

 plain the origin of the Ai^lolepidese, it is only necessary to suppose that, 

 in an analogous structure to that of Funaria, the exterior teeth being 

 wanting, the internal peristome then remained, and this latter in coiu'se 

 of time took upon itself a much more varied and larger development. 



Development of the Sporogonium of Andresea and Sphagnum. J — Dr. 

 M. Waldner has carefully followed the development of the sporogoniuni 

 in these two genera of mosses. In Andreeea he finds that, as is the case 

 in the typical forms of mosses, the spore-forming layer originates in the 

 layers of cells at the base of the sporogonium. The wedge-shaped 

 apical cell forms, by apical growth, from eleven to thirteen segments, and 

 the formation of the sporogenous layer begins in the third oldest seg- 

 ment. In Sphagnum, on the other hand, the first rudiment of the 



* Bot. Gazette, xiii. (1888) pp. 173-8 (1 pi.). 



t Eev. Bryol., xv. (1888) pp. 50- GO, 65-9. Cf. this Journal, ante, p. 020. 

 X 'Die Entwick. d. Sporogone v. Andresea u. Sphagnum,' Leipzig, 1887. See 

 Ocstcrr. Bot. Zeitschr., xxxviii. (1888) p. 281. €f. this Journal, 1880, p. 122. 



