352 BOTANICAL GAZETTE [may 



injurious through their action upon the soil, especially if its unfavorable condition 

 facilitates the formation of H^S. Analysis of plants often shows them to contain 

 an increased quantity of the constituents of the dust. Microscopic investigation 

 of the leaves shows clearly the injurious action of various dusts, which is substan- 

 tiated by tests with the component salts; but there are no typical anatomical 

 marks by which the injury wrought by one kind of dust may be distinguished 

 from another. — C. R. B. 



Polystelic roots • 



Van 



disproved, but it seems clear that the phenomenon occurs in roots. Cormack and 

 later Drabble^? described a multistelic condition in the roots of palms, and a recent 

 research by White^^ pj-^ves its occurrence in both the lateral and the tuberous 

 roots of certain orchids belonging to Ophrydinae. In Habenaria orhiculata the 

 stele of the lateral root is at its base monostelic, farther out it flattens, becomes 

 horseshoe-shaped, then divides into two steles which at the tip merge into a common 

 plerome cyclinder. In H. hlephariglottis a protostele acquires a pith and internal 

 endodermis, then opens out to a horseshoe-shape from the free ends of which 

 steles are constricted; as in the former case these steles merge into a common 

 plerome at the root tip. In iT. hyherhorea the steles are separate from the start, 

 but increase in number as they proceed farther from their origin. In the tubers 



AN 



TiEGHEM founded his theor}- of ''concrescence'' to account for the conditions seen 

 in orchid roots. The present research strongly supports the \iew advanced by 

 Jeffrey as to the extrastelar nature of the pith, for in H. bkphari glottis the pith 

 of the proximal part of the central cylinder merges into the fundamental tissue of 

 the polystele. Moreover, the plerome initials are seen to give rise to both funda- 



correspo 



of plerome and periblem to stele and cortex respectively cannot be maintained. 



Chrv 



Salt marshes of New England.— The construction of an electric railroad 



Maine 

 deposits 



A study of 



^„ -^^v^ujjii Liii. ucjjusitb ueneain me luri oi me marsn. rv siuu; <ji 



such a section by Penhallow? shows that there was an abrupt conversion of a 

 fresh-water bog into a salt marsh by the sudden intrusion of sea water, and that 

 this phenomenon was connected with the gradual subsidence of the general area 

 in which the marsh is situated. It would appear that at some former time (Pho- 

 cene) shallow basins existed between islands along the Atlantic coast, and some 

 of these basin s, being cut ofif by the formation of barrier reefs, were converted into 



"Re^-iewed in this Journal 39:382. 1905. 



I White, J. H., On polystely in roots of Orchidaceae. Univ. of Toronto Studies, 

 Biological Series no. 6. pp. 20. pis. 7, 2. 1907. 



19 Penh.\i.low, D. p., a contribution to our knowledge of the origin and develop- 

 ment of certam marsh lands on the coast of New England. Trans. Roy. Soc. Canada 

 HI. 1^:13-56. 1907. 



I 



