394 BOTANICAL GAZETTE [November 



Leaf structure and physical factors. — Most American ecologists have paid 

 attention to the distributional rather than to the anatomical phases of their sub- 

 ject. For this reason the contribution of Mrs. Clements'^ has been particu- 

 larly welcome. Few if any investigators have so thoroughly related leaf structure 

 to definite physical factors. After a brief historical sketch, and a survey of the 

 physical factors studied (light, water content of the soil, humidity, temperature), 

 a detailed presentation is given of the characteristics of the mesophyll and epi- 

 dermis of a large number of the plant species of various habitats in the Pike's 

 Peak region of Colorado. The plants are divided into tw^o classes, those confined 

 to one habitat, and those that occur in two or more habitats (polydemic species). 

 The latter seem to be the most numerous, and of course are the most interesting, 

 as showing the range of specific variation. The various types of polydemic 

 species are grouped so as to bring out graphically the effects of the various factors. 

 The use of the word endemic for plants confined to one habitat, and mesophyll 

 for a mesophytic leaf seem unfortunate in view of the long and wide use of these 

 words in other senses. Among the more interesting of the results and conclu- 

 sions, we may note that the lack of palisade cells is regarded as adaptational in 

 many hydrophytes, but hereditary rather than adaptational in monocotyls; a 

 typical xerophyte is regarded as having the chlorench}Tna made up entirely of 

 palisade cells; while light is regarded as the dominant factor in determining the 

 palisade structure and close cell texture in xerophytes, dryness of air or soil is 

 necessary for the extreme expression of this result. This paper is one that should 

 stimulate many to carry on work along the lines of ecological anatomy. — Henry 



C. COWLES. 



Tomato rot. — The blossom end rot of tomatoes is again the subject of study. 

 This is a widespread disease which has been studied repeatedly but without con- 

 cordant results. The rot has been heretofore variously attributed to Macrospo- 

 rium, Fusarimn, Cladosporium, and to bacteria, while some workers have failed 

 to find any parasites at all. The latest bulletin, by Miss SiiiTH,^^ describes the 

 discovery, after very careful search, of small tufts of a colorless mycelium, pro- 

 truding from intercellular spaces between the blackened walls into the still healthy 

 tissue. Affected pieces of tissue in a moist chamber repeatedly developed an 

 abundant growth of Fusarium. The affected tissue showed no bacteria. Pure 

 cultures of the Fusarium were isolated and inoculations upon green fruit were 

 successful, sometimes through the style but much more frequently through punc- 



This disease does not develop well or at all upon old 

 )eing limited to young fruit. The writer correlates this 

 ■ malic acid as the fruit increases in size; since her cultures 

 s extremely imfavorable to the errowth of this species of 



ermis 



Fusarium 



i6 Clements, Edith S., The relation of leaf structure to physical factors. Trans 

 Amer. Mic. Soc. 1905:19-102, 



17 Smith, Elizabeth H., Mass. Agr. Exp. Sta. Technical Bull. 3. April 1907. 



