4G0 SUMMARY OF CURRENT RESEARCHES RELATING TO 



when they are always considerably smaller. They are often swollen 

 and glandular at the apex, and may serve both as secretory and as 

 protective organs. The view that these paraphyses are rudimentary 

 sporangia is confirmed by the facts that they are sometimes found 

 divided in the samo way as true sporangia, that in Aspidium Sieboldii 

 the sporangia are normally branched, and that in this species the 

 paraphysis has been found replaced by a sporangium. 



The origin and development of the sporangium agrees with that of 

 the Polypodiacere in all essential points in the Cyatheaccse, Schizaoacere, 

 Gleicheniaccao, and Hyinenophyllaeeae. 



Stomata and Ligules of Selaginella.* — Prof. W. E. M'Nab reports 

 that he lately exhibited leaves of Selagiiiella densa and S. Poulteri, show- 

 ing a triple series of stomata developed along each margin. In leaves of 

 seedling plants of S. Eraussiana the peculiar marginal stomata were also 

 found to be present ; they form three rows, one on the actual edge of 

 the leaf, one on the upper, and one on the lower side ; and in these three 

 species the elongated sclerous cells which are often found on the margin 

 of the leaf are wanting. The marginal stomata are easily demonstrated 

 by carbolic acid, which renders the whole part exceedingly transparent. 

 In such preparations the course of the fibrovascular bundles can be 

 easily traced, and the relation of the ligule to the bundle clearly made 

 out. The author suggests that the ligule is an organ of absorption. 



Museineae. 



Anatomy and Development of the Sporogonium of Mosses.f — 

 Mr. J. E. Vaizey holds that the Muscinea3 are not separated from the 

 Vasculares by so great a gap as has been usually supposed. 



The Polytriehacese are a favourable group for the examination of the 

 structure of the sporogonium, as they are easily obtained, and their 

 large size makes the examination of minute structure in them easier 

 than in most of the other common orders of Musci. The author 

 summarizes his conclusions as follows : — 



(1) The tissues of the central strand in the cases investigated 

 consist of two kinds, the leptophloem whose function is inferred on 

 anatomical grounds to be similar to that of the phloem of Vascular 

 Plants, and the leptoxylem, the function of which was originally inferred 

 on anatomical grounds, but has lately, by direct experiment, been deter- 

 mined to be that of conducting the transpiration current up the seta. 



(2) The apophysis of the sporogonium of the Polytriehacese is an 

 organ for assimilating and absorbing gases, and that transpiration takes 

 place from it must be evident from ite anatomy ; and it is in this respect 

 similar to the leaves of vascular plants. 



(3) The foot (the portion of the sporogonium placed within the 

 vaginula) is the organ of absorption of fluids, although it does not 

 present the ordinary form of a root, as it does not show any sign of 

 endogenous structure. 



The author suggests that the root of Phylloglossum may form a 

 connecting link between the foot of the Museineae and the root of the 

 Vasculares. 



* Eep. Brit. Assoc. Adv. Sci., 1887 (1888) pp. 743-4. 



t Journ. Linn. Soc. Loud.— Bot., xxiv. (1888) pp. 262-85 (4 pis.). Cf. this 

 Journal, ante, p. 91. 



