Pteridophyten. 193 



compared to those of D. conjiigata: though agreeing in the main 

 with those of D. bifurcata the sporangia and sori of D. conjugata 

 are smaller and its leaf is wider. In these respects, D. qinnqiiefur- 

 cata is intermediate between the two other species. It is suggested 

 that the three species constitute a series of which D. bifurcata is 

 the most primitive member. It is believed that there has been first 

 a widening and then a webbing of the pinnules to form a broad 

 expanse and at the same time an increase in the number of sori, 

 and a decrease in the number of sporangia in each sorus, accom- 

 panied by a transition within the genus from the type of sorus 

 found in the Simplices (in which all the sporangia of a sorus are ot 

 the same age) to that of the Mixtae (in which the sporangia of a 

 sorus are of different ages). A parallel case of transition within the 

 confines of a genus is noted in Dennstaedtia where, however, the 

 transition is from the type of the Gradatae to that of the Mixtae. 



Isabel Browne (London). 



Benson, M., The Sporangiophore — A unit ofStructure 

 in the Pteridophyta. (New Phytol. Vol. VII. p. 143—149, with 

 2 textfig. 1908.) 



Miss Benson notes the prevalence of a sporangiophore in the 

 Spheyiophyllales, Eqidsetales and Psilotales, and points out the wide 

 ränge of its structure, varying, at is does, from a monosporangiate 

 to a pol3^sporangiate, from a sessile to a pedicellate and from a 

 dorsiventral to a radial organ, and being, moreover, borne on the 

 leaf or the axis. It is suggested that the Lycopodineous 'sporange' 

 is S3'nangial in origin and a reduced structure homologous with a 

 sporangiophore. In support of such a theorj^ figures are given of 

 the sporophyll of two undescribed Palaeozoic types, Masocarpon and 

 Lepidostvobus masocarpon. Stress is laid on the resemblances of the 

 sporangiophore or synangium of the Lycopsida and the synangium 

 or sorus of the Pteropsida. It is held that a generalized type of 

 sporangiophore gave rise to the "synangium" of Marattia, the "sorus" 

 of Matonia, the "sporange" of Lepidostrobus , the "sporangiophore" 

 of Eqiäsetian and the "synangium" of Tenesipteris. It is thought that 

 sporangiophores as well as certain adventitious sterile structures 

 found on the axis and rachis of several Palaeozoic ferns may be 

 Units, still existing as relics from the Propteridophytic thallus. 



Isabel Browne (London). 



Boodle, L. A., On the Production ofDwarfMaleProthalli 

 in the Sporangia of Todea. (Ann, Bot. p. 231 — 243 with 1 plate. 

 1908.) 



The author found a filmy Todea in which the spores had ger- 

 minated within the sporangium and at once formed antheridia. In 

 Order to ascertain the reason of this precocious development T. 

 Fraseri and T. hy>nenophylloides were subjected to experirhents. 

 Typicall}'' only a few spores germinate within the sporangium and 

 not all of these develop antheridia. Free spores and spores enclosed in 

 the sporangium were kept under similar conditions. After numerous 

 experiments with various parallel cultures, the general result obtained 

 was that dwarf male prothalli with antheridia were found in several 

 sporangia but were never produced by free spores; the latter develop 

 normal prothalli. Experiment showed that the dehiscence of the 



Botan. Centralblatt. Band 111. 1909. 13 



