THE GKNUS CON lOTHECIUM . 65 I 



Massee, in his paper referred to, wrote : " Hence, in future 

 Coniothecium will only be retained as a form-genus until its com- 

 ponents are correlated with their respective PJionia forms." His 

 evidence is briefly this : ( i ) The appearance of the Phoma stage 

 when budding Coniothecium spores are sown in petri-dish cul- 

 tures ; (2) Phoma spores from these cultures gave origin first to 

 the Coniothecium and afterwards to the Phoma condition; (3) 

 Phoma spores from above source when placed on young apple 

 shoots gave origin to the Coniothecium condition of the fungus. 



In addition, he holds that the ascigerous stage of the fungus 

 is Diaporthe ambigua Nits. He met with this stage only once 

 accompanying the Phoma on a dead apple twig. These ascigerous 

 spores on nutrient media gave origin to the Phoma without the 

 intervention of Coniothecium, which, however, formed when the 

 Phoma spores were sown. 



The author holds that the Phoma and DiaportJie forms are 

 l)ure sajH'ophytes appearing on the branches killed by the Conio- 

 thecium, which is the only parasitic form included in the life-cycle 

 of the fungus. 



The relationship of the fungi known as Coniothecium chonm- 

 tosporuui Corda, Phoma Mali Schulz. & Sacc. and Diaporthe 

 ambigua Nits., he regards as fully established, and goes further, 

 as is seen from the paragraph quoted above. 



The author* states that C. O. Farquharson, in an incom- 

 pleted investigation on a water-lily disease, was the first to 

 demonstrate that Coniothecium resulted from the germination of 

 Phoma spores, and that subsequently he proved that the spores of 

 Phoma abietis Br. produced on germination a ConiotJiccium 

 stage. 



Other writers have regarded Coniothecium as forming part 

 of the cycle of fungi other than those enumerated, but as the 

 original works were not available, the reader must refer to 

 Gueguent for the references. 



Present Observations. 



1. Blister Disease of Fruit Trees and Cracking of Fruit. 



Blister disease (PI. 29, b) is of frequent occurrence on the 

 branches of apple and pear trees in South Africa, and a surface 

 section shows us the olive-coloured mycelium giving rise to 

 clusters of large globose cells (PI. 29, d, and PI. 30, a) — the Conio- 

 thecium stage of the fungus. The blackish olive colour of the 

 blisters is due to the dark colour of the fungus. 



A transverse section through a " blister" (PI. 30, b) shows us 

 the olive brown cells of the fungus between the cells of the host 

 ])lant. The fungus evidently invades the middle lamellje of the 

 cells, as is evident from both surface and transverse sections. As 

 a result, the cells separate, press outwards, and thus ultimately 

 the skin over the blister is ruptured. 



* Op. cit., p. 106. 

 to/', cit., pp. 151-155- 



