October 25, 1901.] 



SCIENCE. 



6dI 



conclusions are reached, among which are 

 the following : There is a slight variation in 

 the roots as regards branching and vascular 

 limits ; in the stem there is a great range of 

 structural deviations, which take place along 

 definite lines and by defiuite steps, the varia- 

 tion exteadiug to bundle branching and reticu- 

 lation, extent of succulence, character of par- 

 enchyma, of pith and cortex, development of 

 mucilage, and even to the kinds of elements 

 entering into the xylem. Suggestive results 

 from the systematic point of view were also 

 obtained. Alfred Rehder has written upon 

 Vasilima and Schizonotus of Rafinesque, both 

 of which he regards as properly synonyms of 

 Sorharia. Arthur Bennett makes the first 

 record of the appearance of Potamogeton poly- 

 gonifolius in Newfoundland, the only other 

 known North American situation being on the 

 island of Nova Scotia. 



In the numbers for August and September 

 three continued papers appear. Dr. F. L. 

 Stevens has written upon ' Gametogenesis and 

 Fertilization in Albugo ' ; and Dr. W. L. Bray 

 upon ' The Ecological Relations of the Vegeta- 

 tion of Western Texas.' Both of these papers 

 will be noticed upon their conclusion in the 

 October number. The third paper is by Dr. 

 Florence May Lyon, entitled ' A Study of the 

 Sporangia and Gametophytes of Selaginella 

 apus and S. rupestris.'' The description of S. 

 apus is the first account yet published of the de- 

 tails of development of both gametophytes of 

 any species of Selaginella. A preliminary study 

 of the megaspore and female gametophyte of 

 S. rupestris is added. The most striking fact 

 observed is the persistent retention of the mega- 

 spores within the unshed sporangia throughout 

 the formation of the prothallium and of the 

 embryo. In the case of S. rupestris, at the 

 time the strobilus is separated from the plant 

 by the decay of the vegetative part beneath, 

 it appears covered with sprouting plantlets. 

 The megaspores of S. apus are shed before the 

 embryo has emerged. The significance of this 

 sequence of events lies in the resemblance to 

 the formation of seeds in the higher plants. 

 But one or two megaspores of S. rupestris form, 

 whereas the normal number four appears in S. 

 apus. The description of the male gametophyte 



differs from that given by BelajefF. It consists 

 of a single cell, presumably the vestige of the 

 prothallium, and the two masses of spermato- 

 zoid-produclng cells. Fertilization is accom- 

 plished in a manner suggestive at least of the 

 seed plants. The mlcrosporangia open with 

 force when the male gametophytes are mature, 

 and the latter are shed like pollen grains. 

 The outer wall of the microspore has cracked 

 open at this stage and the endospore protrudes 

 in a papilla-like protuberance like a very short 

 pollen tube. This ruptures and the spermato- 

 zoids are freed In a mass of slime that is at- 

 tracted toward the archegonia. Microspores 

 were found within the megasporangia, having 

 been hurled in when the latter were gaping 

 open. The bryophyte-like character of the 

 spermatozoids claimed for the Lycopodiacese 

 was not demonstrated in these two species. 

 As regards their form they were typically fern- 

 like, spirally coiled, and the presence of cilia 

 not determined. The methods by which the 

 strobili were sectioned with their nut-like spores 

 in situ is given in detail. 



In all the numbers there are the usual ' Briefer 

 Articles,' 'Reviews of Current Literature' and 

 ' News Items.' 



The August number of the American Geolo- 

 gist contains a history and biographical sketch 

 of the late George M. Dawson, of Canada. 

 The paper is accompanied by a portrait of 

 Mr. Dawson and a bibliography of his writings. 

 ' The Pleistocene Problem of the North Atlan- 

 tic Plain,' by Geo. Shattuck, contains a discus- 

 sion of the views of W J McGee and N. H. 

 Darton followed by those of Professor R. D. 

 Salisbury. The writer concludes by stating 

 his own views based on considerable field work 

 in the area. He claims that five terraces have 

 formed in this period and he approaches their 

 study through a study of the present work of 

 the Chesapeake and the Atlantic Ocean. For 

 these four formations below the present terrace 

 he proposes the following names : (1) Talbot, 

 (2) Wicomico, (3) Sunderland, (4) Lafayette. 

 In the editorial comment is an extended descrip- 

 tion of ' The Department of Geology in the Na- 

 tional Museum.' This discussion is accompanied 

 with five plates illustrating types of the various 



