522 FUNGI IMPERFECTI. 



are sparse foliage, small yellowish leaves, and death of the 

 smaller branches over the tree. Sweet seedling orange (Cifrus 

 aiirantiuvi) and lemon {C. livionum) are most subject to this 

 malady, the grape-fruit {C. decumana) is only slightly liable, 

 and the sour orange {C. higaraclia) is almost wholly exempt. 

 For this reason sour orange stocks should be used on lowlands 

 and flatwoods, and grape-fruit stocks on the higher lands. The 

 most effective treatment is to remove the soil around the crown 

 roots by using a jet of water. Diseased bark should also be 

 cut away and the wounds painted over with carbolic acid or 

 sulphur wash. Good drainage to promote root aeration and 

 the avoidance of excessive use of nitrogenous manures are also 

 recommended. 



Fus. vasinfectum Atks.^ A species found by Atkinson to 

 cause a cotton-disease known as " frenching." This consists in 

 a discoloration of the leaf from the margins inwards, at first 

 pale or yellow, but turning to brown. A mycelium was found 

 in the tissues of the stem, causing the vascular bundles to 

 assume a light brown colour. The host-plants are either killed 

 or so seriously affected that the crop is injured. The conidia 

 formed are of the pleuriseptate slightly curved Fusarium type. 



Atkinson - in the course of his investigations on carnation 

 diseases found a Fusarium present in all cases of the " carnation 

 rosette." The stems remain short and stunted with their leaves 

 small and crowded together. A mycelium was present in the 

 tissues of the stem and caused discoloured spots. 



II. THE PATHOGENIC SLIME-FUNGI. 

 MYXOMYCETES. 



The Myxomycetes ^ rank amongst the lowest of i^lant-forms. 

 They show so close relationship to the lowest animals tliat 

 certain groups {Monadina) receive greater consideration from 

 the zoologist than from the botanist. They exhibit in their 



^Atkinson, "Cotton Diseases," Alahama A<irlc. Exj)a'. Sfatioii. Bulletin, No. 

 41, 1892. (Kdit.) 



-^^ Carnation Diseases" at American Carnation Society, 1S93. 



=*The more important literature dealing with this family will be found in: 

 De Bary, Morphology and Biology of the Fungi (English Edition) ; Lister, The 

 Myceto-Ma, London, 1895; Zopf in Schenk's Handbuvh der Botanik, iii., 1887; 

 Schroeter, "Myxomycetes" in Die naturlich. Pjlamev/amilien, i., 1892. 



