10 July, 1917.] Anthiaciwse or Black Spot of the Vine. 409 



Until recently its life history was only imperfectly understood, but the 

 researches of Viala and Pacottet, first published in 1904, liave enlightened 

 us very fully on the subject. These investigators found the fungus to 

 be a most remarkable one, being extremely polymorphic, or, in 

 other words, capable under given conditions of assuming a great variety 

 of distinct forms. 



Manginia diffei-s entirely from Oidium (an external fungus) in that 

 its mycelium* is internal to the tissues of the vine. The germinating spore 

 sends out a filament or mycelium tube which penetrates the surface and 

 spreads amongst the tissues, disorganizing them to such an extent that 

 thev sink in and form the characteristic scars on canes, leaves, and 

 berries. In this internal nature of its mycelium it resembles most other 

 vine fungi, and for this reason curative treatment is of no avail against 

 it. It is evident that once entry into the tissues has been effected, the 

 mycelium is sheltered from any fungicides which might be applied 

 againsti it. In this it differs radically from Oidium, the external 

 mycelium of which is readily got at and destroyed by sulphur, perman- 

 ganate, and similar fungicides, thus rendering curative treatment not 

 only feasible but fruitful of excellent results. The internal mycelium 



Fig. 6. 



Diagrammatic section of a scar in early summer showing 

 how spores o, are produced on the closely-packed, erect fila- 

 ments 6, thrown up from the more or less decomposed tissues c, 

 containing the mycelium of the fungus, though the latter is not 

 easy to distinguish. (x 4.50) After G. Foex. 



The spores give the pinkish colour to the centre of the sear; 

 they are produced in enormous numbers, and spread the 

 disease if weather conditions permit of their germination. 



of Manginia sends out spore-bearing filaments on which are born the 

 conidia, or summer spores, by which the disease is spread during early 

 summer. These filaments are closely packed, as is shown in Fig. 6, con- 

 stituting a sjx)re-bearing apparatus bolanically known as a stroma. f 

 Thus, a single scar arrived at the fruiting stage is capable of sending out 

 an enormous number of spores. The production of these spores is marked 

 by the ashy-pink colour of the centre of the scars already referred to. 

 Until 1904 these were the only reproductive organs of the fungus which 

 were really well known, though the existence of others was suspected. J 



In 1904 Viala and Pacottet, in lectures to students of the French 

 Institut Agrinomoque described for the first time the true life history 



• Mycplhim Is thus defined by dc Bary — " Vegetative rortlon of thallus of fungi, composed of one or 

 more hyphac." The mycelium is the growing (and feeilint) portion ol the fungus as ilistingnished from 

 the spore- bearing or reproductive part. In edible, cultivated mushrooms it is popularlv linown as spawn. 



t A stroma is defined by de Bary as follows : — Compound fungus body having the form of a cushion, 

 crust, follaceous expansion or erect unbranched or branched shrub-like body — same as rcceptaculum. 



: In " Les Maladies de La vigne " (1893 addition) P. Viala quotes Goethe as having observed a kind 

 of pycnidinm on the swollen edges of Anthracnose scars — also Prillieux and ^fax Cornu, who had made 

 similar observations. The similaritv of the coneeptacles to those of Black Rot led Cornn to think that 

 the two diseases might be di.lerent forms of the same fungus. Viala has shown this opinion to be 

 groundless. 



