262 SUMMARY OF CURRENT RESEARCHES RELATING TO 



sporangia pendent in the form of a fringe ; pinn^ dimorphic. Calym- 

 natotheca Stur. Dactylotheca n. g. — sporangia exposed, especially on 

 the inferior lobes, almost like the fingers of a hand. Benaultia n. g. — 

 sporangia resembling those of Angiopteris, but isolated. Myriotheca 

 n. g. 



11. Sporangia with annulus : — Senftenhergia Corda. OUgocarpia 

 Gop. (Gleicheniacese). Hymenophyllites Gop. (Hymenophyllacese). 

 Biplotmema Stur. Grand'Eurya n. g., nearly allied to Zygopteris. 



The author considers that the family Botryopteridaceae formed 

 by Renault should be regarded as ranking with Gleicheniace^, 

 CyatheaceaSj and Polypodiacese, if not with Marattiacese. 



Prothallium of StrutMopteris germanica.* — D. H. Campbell has 

 cultivated the spores of this fern, and finds the prothallium to be 

 distinctly dioecious. The male and female prothallia difffer some- 

 what in form, the former being more distinctly heart-shaped. 



Muscinese. 



Mucilage-organs of Marchantiacese.t — Organs containing muci- 

 lage have been recently described by several observers in different 

 species belonging to the Marchantiacese. E. Prescher has examined 

 them in detail, with the following results : — 



Organs of this kind occur in a large number of species, usually 

 in the form of isolated mucilage-cells, as in Marchantia polymorpha, 

 cartilaginea, clienopoda, and paleacea, Preissia commutata and quadrata, 

 Clevea hyalina, and Plagiochasma Bousselianum. Fegatella conica 

 contains in addition mucilage-tubes. The mucilage-cells occur in the 

 thallus, and in the male and female receptacles, and especially in the 

 tissue without intercellular spaces ; they are found in the greatest 

 numbers immediately beneath the layer which contains the air- 

 chambers ; less often they occur also in the epidermis, as in M. 

 cartilaginea and ckenopoda ; and in the septa of the air-chamber layer, 

 as in M. clienopoda, Clevea hyalina, and Plagiochasma Bousselianum. 

 The mucilage- tubes of Fegatella conica are found exclusively in the 

 tissue of the mid-rib of the thallus, which has no intercellular spaces. 



All the organs which contain mucilage are differentiated at a very 

 early period near the growing points. They are distinguished in 

 their youngest state by their thin cell-walls and abundant protoplasm. 

 Several segments usually go to the formation of a mucilage-tube. 



The mucilage is formed out of the protoplasm, which never con- 

 tains starch. It lies in contact with the primary cell-wall, in the 

 form of a thin layer which gradually becomes thicker, and displays 

 from the first its peculiar chemical and physical properties. It is 

 highly refractive, and has great power of swelling ; treated with 

 alcohol, it displays stratification, and a brownish colour ; its yellow 

 reaction with iodine and sulphuric acid indicates an affinity with 

 vegetable gum. In older parts of the thallus both cells and tubes 

 are completely filled by mucilage ; protoplasm is essentially con- 

 cerned in its formation. 



* Bull. Torrey Bot. Club, x. (1883) pp. 118-9. 



t SB. Akad. AViss. Wien, Ixxxvi. (1882) pp. 132-58 (2 pis.). 



