ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 613 



cabbage-leaf spot. The green leaves of cauliflowers and cabbages are 

 attacked by a fungus now described as I'hyllosticta brassicicola which 

 appear as minute black dots. The perfect fruiting form, Mycosphserella 

 brassicicola, appears much later in the season. The connexion of the 

 two forms seems to be correctly assumed, though it has not been proved. 

 The outer leaves of the cabbage are attacked first. The disease has 

 recently been introduced into America. It has long been known in 

 Europe and in Australia. 



Lichens. 

 (By A. Lobrain Smith, P.L.S.) 



Lichens of Perthshire.* — J. A. Wheldon and Albert Wilson have 

 published a list of lichens for this county compiled from various records, 

 and added to by their own labours extending over a period of ten years, 

 but they do not consider the record by any means exhaustive. They 

 preface the systematic portion of the paper by an account of the physical 

 and climatic features of the country with reference to the occurrence 

 and growth of lichens. They divide the plants into three ecological 

 zones : (1) the zone of cultivation and pasture ; (2) the zone of closed 

 moorland associations ; and (3) the Arctic Alpine zone. There are 

 many new records for the county. A new genus, Pyreniococcus, allied 

 to Obryzum, is described, and several new species or varieties. 



Ecological Study of Lichens.t — R. C. McLean has described the 

 occurrence and distribution of lichens over a restricted seaside area at 

 Blakeney Point, Norfolk. He describes the climatic conditions, one of 

 the most important for lichens being a heavy dew-fall, and then gives a 

 list of lichens found in the area. Where the ground was covered by 

 grass, Cladonia furcata and Getraria aculeata were abundant ; when stones 

 were in the ascendant, saxicolous species were dominant. He delimits 

 a certain number of associations : Bare sand, on which are found plants 

 of Cladonia and Getraria probably blown there ; grey dune, derelict 

 dune, high shingle, loose shingle, round shingle, and low shingle, the 

 plants found on these being enumerated. He then considers the 

 " Distribution in relation to Edaphic Factors," that is, with regard to 

 sand, humus, and mud, and correlated with these the relative stability 

 of the substratum. 



The growth of individual thalli was also watched. He decided that 

 the fruticulose lichens were the most rapidly growing ; the thallose 

 species occupy an intermediate position, while the crustaceous species are 

 the most slow growing of all. Marked lichens were tested as to the rate 

 of growth, but the time covered by the experiments is not given. 



Phases of life-histories, that is, the growth and decay of certain 

 species, is touched on, and species with anomalous distribution are 

 described. He concludes that lichens cannot be considered ecologically 

 apart from the phanerogamic vegetation. 



* Journ. Bot., 1915, Supplement, 74 pp. 



t Journ. Ecology, iii. (1915) pp. 129-48 (3 figs.). 



