ZOOLOGY AND BOTANY, MICROSCOPY, ■ ETC. 195 



Sporangial Development in Equisetum hyemale.* — L. A. Hawkins 

 gives an account of the development of the sporangium of Equisetum 

 hyemale, and claims that the plant " is of the eusporangiate type ; the 

 sporogenous tissue comes from a single cell ; the first wall is peridural, 

 the inner cell being sterile, while the sporogenous tissue comes entirely 

 from the outer cell ; the tapetum comes from the cells surrounding the 

 sporogenous mass ; there are two types of sporangia differing in develop- 

 ment and governed by the direction of the second division ; many of 

 the sporocytes are disintegrated during the formation of tetrads." 



Inner Roots of Lycopodium pithyoides. t — A. G. Stokey describes 

 the structure and development of the roots of Lycopodium pithyoides, an 

 epiphytic Pteridophyte transplanted from Mexico to Chicago. It 

 resembles a young Pinas sylvestris ; and practically every leaf is a sporo- 

 phyll. But more striking than the general habit is the appearance of 

 the stem in transverse section. The stele is small, and not remarkable, 

 but is conspicuously surrounded by numerous smaller heavily sheathed 

 steles. These are the " inner roots " described by Strasburger as existing 

 in certain species of Lycopodium. They arise in acropetal succession at 

 any point of the stele, and, instead of penetrating the cortex at once, 

 and emerging as aerial roots, they turn downwards, and, boring through 

 the cortex, emerge finally at or near the base. This habit is associated 

 with erect forms of Lycopodium, both terrestrial and epiphytic. Stokey 

 describes the development and structure of these roots in L. pithyoides, 

 giving some comparative notes on other species. 



New Palaeozoic Lycopod. J — M. Benson describes shortly a new 

 palaeozoic Lycopod with a seed-like structure. The vegetative organs of 

 this plant, Miadesmia membranacea, were discovered by Bertrand in 

 1894, in sections of a calcite nodule from the Gannister beds of Hough 

 Hill. From an examination of much new material, further details are 

 known as to the vegetative organs, as well as a fairly complete account 

 of the reproductive organs. Miadesmia was very minute, with a slender 

 stem and without any trace of skeletal tissue. It is the first palaeozoic 

 Lycopod of herbaceous character known structurally. The megasporo- 

 phylls were identified by D. H. Scott in 1001, and they show a more 

 advanced type of seed habit than has hitherto been met with in 

 Cryptogams. The megasporangium gives rise to but one thin-walled 

 spore, which in development and structure resembles an embryo-sac 

 and germinates in situ. An integument surrounds the sporangium, 

 leaving but a small orifice as micropyle. This is surrounded by numerous 

 long processes of the integument, which formed a collecting and 

 incubating apparatus for the microspores. There is no trace of an 

 envelope about the microsporangium. The carpellary leaf was shed at 

 maturity, and resembles a winged seed. Apart from structural modi- 

 fications of the megasporophyll, Miadesmia is most closely allied to 



* Ohio Naturalist, vii. (1907) pp. 122-8 (2 pis.). See also Bot. Gazette, xliv. 

 (1907) p. 78. t Bot. Gazette, xliv. (1907) pp. 57-63 (2 pis.). 



X Proc. Roy. Soc, Series B, lxxix. (1907) No. B 534, p. 473. 



