1108 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



DlCTYOSTELIUM MUCOROIDES. 



Dictyostelium mucoroides, The Physiology of. By George 

 Potts, D.Sc. (Flora, vol. xci. 1902, pp. 281-317 ; 4 cuts).— This is an 

 interesting member of the Acrasiece, differing from the true Myxomycetes 

 in its not possessing rlagella at any stage, nor forming a true plasmodium, 

 the amoebulas simply multiplying by fission, and aggregating to form 

 a fructification, the lower and central ones being sterilised as a stalk and 

 central axis up which the others creep to form an oval assemblage, and 

 then encyst as spores. It was found by cultures on agar-jelly containing 

 various nutritive substances the amoeba? do not take in bacteria, but kill 

 them and are nourished by absorption of the products. It grows better 

 on a solid than a liquid substratum, preferably slightly alkaline rather 

 than acid. In liquid the fructification is spherical, no stalk being formed 

 as in air. Maize extract was found the most suitable nutritive substance. 

 Incidentally a new bacterium was found, very suitable for feeding the 

 Dictyostelium, and described as Bacterium fivibriat um, from the fringing 

 outgrowths along the needle's path in gelatine cultures. — M. H. 



Ecology of Delaware. 



Ecology of Delaware Coast. By L. M. Snow (Bot. Gaz. xxxiv., 

 p. 284, No. 4 ; with map and 10 photos). — The portion studied was 

 between six and seven miles long and from one half to a mile wide along 

 the Atlantic coast. After describing the topography, soil, and climato- 

 logy, the author deals with plant formations as follows : — A. " Treeless 

 open," consisting of the beach formations, dunes, and heath. B. Wooded 

 region. The first place of vegetation is secured by the accumulation of 

 sand and driftwood, Sec. Here species of Cakile, Salsola, Xanthium, and 

 A triplex occur ; on the next zone Ammophila establishes itself. Higher 

 up Panicum amarum, Cenchrus tribuloides, &c. are added. The dunes 

 are divided into four series. The outer consists of " Pine graveyards," i.e. 

 the remains of the forest over which the dunes are now passing. The 

 next lies behind the former as a general depression characterised by 

 Iluchonia tmncntosa. Swamps and meadows extend among these dunes. 

 " Silver-lake " occurs in them, around which is Scirpus americanus, 

 Cyperus Bp., Polygonum maritimum, &C. ; while more xerophytic forms 

 appear on low elevations. 



The heath region starts from the second series and extends back to 

 the forest, containing a large number of species with few characteristic 

 forms, such as Baptisia tinctoria, Bubus sp., Junipcrus virginiana, 

 Pinus rigida, Sec. Lastly is the wooded region and forest formation, con- 

 taining Quercus digitata, &c, and Carya ovata. — G. H. 



Embryology. 



Embryology of Cynomorium {Beih. Bot. Cent. bd. xiii. ht. 2, 

 pp. 194-202). — Professor Dr. 0. H. Juel (Upsala) describes the morpho- 

 logy and development of the embryo of Cynomorium coccincum. The 

 embryo-sac mother-cell divides into four daughter-cells. The micropyle 

 becomes obliterated, though the pollen-tube enters in the micropylar 



