388 SCIENCE PROGRESS 



Jour. Set. 46, 240, 191 8) discusses the mineralogical work of 

 the past hundred years, and R. B. Sosman (ibid. 255, 191 8) 

 refers to the work of the Geophysical Laboratory. 



BOTANY. By E. J. Salisbury, D.Sc, F.L.S., East London College, 

 University, London. 



Anatomy. — Dr. J. M. Thompson has studied the anatomy and 

 affinity of ferns belonging to the genera Jamesonia, Llavea, and 

 Trismeria (Trans. Roy. Soc. Edin. vol. lii. pt. ii.). All three 

 genera exhibit a solenostelic structure, which is most advanced 

 in its construction in Trismeria. The sporangial arrangement 

 is " acrostichoid " and the number of spores small in Trismeria 

 and large (over sixty- four) in Jamesonia. In the former genus 

 the pinna traces are mostly extra-marginal, whilst in the other 

 two genera their origin is marginal. The author concludes 

 that the groups have an affinity, though this is not very close, 

 and have been derived from a Schizeaceous source. 



The phloem of some fifty-five species of woody Dicotyledons 

 has been examined in both the seedling and adult conditions 

 by L. H. Macdaniels (Am. Jour. Bot. July 191 8). From this 

 study he concludes that there are no fundamental differences 

 in the type of sieve-tube, in the mature phloem and that of 

 the seedling, except such as can be correlated with the 

 smaller size of the elements in the latter. Moreover, the sieve- 

 tube with single transverse plates (herbaceous type of Hemen- 

 way) is probably as frequent as other types in the arboreal 

 forms studied. Even within the same genus Fraxinus ameri- 

 cana has sieve-tubes with oblique end-walls and several plates, 

 whilst the sieve-tubes of F. nigra have but a single plate, 

 which is either transverse or slightly oblique. By contrast 

 the Salicacese, Betulaceae, and Juglandacese very constantly 

 exhibit the oblique-ended type with numerous sieve-plates. 

 Companion cells were found in every species studied, but 

 appear to be more prevalent in the higher forms. 



In the current number of the Annals of Botany (July) 

 Prof. D. H. Campbell describes the structure of three species 

 of Dumortiera and Wiesnerella denudata. In D. velutina there 

 are outlines of air-chambers on the upper surface, and the 

 assimilatory tissue is represented by numerous superficial 

 pupillate cells. A new species, D, calcicola, is described which 



