ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 107 



condition, and develops no sexual organs. The terminal cell tlien 

 divides longitudinally ; and, after a number of divisions in both 

 directions, one of the terminal cells takes the lead and becomes a 

 triangular apical cell, which again becomes obliterated towards the 

 close of the growth of the prothallium. The above process is subject 

 to variations. 



In the two species above named, and in Asplenium filix-foemina, it 

 was exceptional to find both kinrls of sexual organ on the same pro- 

 thallium ; while Aspidium spinulosum is generally monoecious. In 

 Cystopteris fragilis two forms of prothallium were found, smaller 

 male, and larger hermaphrodite. The male prothallium is, as a rule, 

 much smaller than the female, and of very irregular shape. Either 

 no definite apical cell is formed, or it is early lost ; not unfrequently 

 the prothallium is reduced to a single row of cells, terminating in an 

 antheridium: and in Asplenium filix-foemina even to a single cell, besides 

 the root-hair, which produced an antheridium with perfect antherozoids. 

 In this same species, on one occasion, the prothallia produced in the 

 summer large numbers of antheridia ; growth ceased entirely in the 

 winter, but was resumed in the spring, when archegonia were produced 

 in large numbers, and subsequently young plants. 



Budding on Apogamous Prothallia of Ferns,* — Dr. H. Leitgeb 

 has studied especially two of the five cases described by De Bary of 

 the apogamous development of shoots on fern-prothallia. One of 

 these is when a shoot appears in the normal position, and a second 

 shoot opposite to it on the dorsal side of the prothallium. This 

 results, according to the author, from alternations in the degree of 

 illumination. In the second case, the primary members of a single 

 shoot distribute themselves over both surfaces of the prothallium. 

 This is also the result of varying degrees of relative illumination on 

 the two sides of the prothallium, combined with the fact that the roots 

 of fern-embryos are always strongly negatively heliotropic. 



Carboniferous Lycopods.j — Mr. E. Kidston describes three new 

 species of Sigillaria {S. McMurtriei, S. coriacea, and S. Walchii), and 

 one of Lepidodendron (L. Peachii). 



Muscineae. 



Section Harpidium of Hypnum.J— Sig. G. Venturi publishes a 

 monograph of the Mosses coming under this subgenus, which he de- 

 scribes as, with but few exceptions, growing in watery places, ditches 

 and ponds, where they form dense tufts, the green extremities of the 

 branches alone emerging from the water. They have also the power 

 of creeping over moist soil, and produce their fructification especially 

 in such situations. The species comprised by the author in this 

 section are Hypnum fluitans, intermedium, verrucosum, aduncum, Kneiffii, 

 Sendtneri, capillifolium, Hausmanni, and riparium, which are described 

 in detail, with their numerous varieties. 



* Ber. Deutsch. Bot. Gesell., iii. (1885) pp. 169-76. 



t Proc. R. Phys. Soc. Edin., viii. (1885) pp. 415-24 (1 pi.). 



X Nuov. Gioru. Bot. Ital., xvii. (1885) pp. 161-84. 



