54 



FIRST REPORT ON ECONOMIC BIOLOGY. 



and ultimately reaches the seed. It now makes its way through the 

 seed coat and establishes itself there. It may entirely destroy the 

 seed, or what is usually the case, the seed ripens and encloses the 

 fungus, which remains dormant. Seeds so attacked have brownish or 

 yellowish coloured patches. If badly attacked they become partly 

 shrivelled. 



Anrhracnose Spores 



much magnified 



Germinated 



FIG. 24 Magnified view of 

 the spores, one of which has 

 germinated. (After Whetzel). 



Anrhracnose Canker 



Bean Pod cut across. 



FIG. 25. Diagrammatic 

 section across a bean pod 

 through an anthracnose 

 canker. (After Whetzel). 



When such seeds are planted in the spring the fungus develops, 

 forms spores and infects the young seedlings as already described. 



PREVENTIVE AND REMEDIAL MEASURES. 



Numerous experiments have been made with soaking the seeds in 

 formalin, etc., but as the fungus is internal the results of seed treat- 

 ment have not proved satisfactory. 



Epidermis or 

 Skin of Pod 



Germ Tube 

 Spqrej 



Mycelium 



Dead Tissue 

 .Mycelium 



'Seed Coat 



Starch' 



FIG. 26. Enlarged view of portion of Fig. 25, showing the mycelial threads of the fungus 

 penetrat'ng the seed coat and entering the starchy tissue of the seed, there to remain 

 dormant until the following season. (After Whetzel). 



