E. S. Salmon and H. Wormald 3 



of water the mucilaginous matrix binding the conidia together is dissolved 

 and the conidia themselves stream apart and become diffused through 

 the water; a slight "Brownian movement" is to be detected when the 

 conidia are mounted in water. 



Transverse sections through the bark show the fungal fructifications 

 to be pycnidia. These bodies are more or less circular in outKne and 

 are from 250 fi to 600 [x in diameter ; they are somewhat flattened and 

 are therefore lenticular, appearing elliptical in transverse section. The 

 pycnidia are produced a little below the surface, but on approaching 

 maturity each develops a short neck which ruptures the outer layers 

 of the bark and the tendril emerges through an apical pore. The wall 

 of the pycnidium is lined with the conidiophores which are from 15 ju- 

 to 25 n in length and which abstrict the conidia from their apices. 



The conidia are continuous, eUipsoidal to fusiform, often with one 

 extremity more rounded and broader than the other. Their dimensions 

 are 6-5-13 x 2-4-3-6 fj,. Usually they are about 9 x 3 /x and as a rule 

 an increase of length is associated with a decrease in the width ; thus 

 the following dimensions are typical: 6-5 x 3-6, 9-2 x 3, ll-S x 2-5, 

 13 X 2-i. With medium magnification they appear to be biguttulate, 

 but by employing an oil-immersion objective this appearance is seen to 

 be due to two groups of minute guttules. The two groups may merge 

 into one another but usually they are quite distinct and situated at 

 opposite ends of the conidium (see Fig. 10, Plate II). 



The conidia are capable of germinating in water. When placed 

 in a hanging-drop of distilled water and examined after remaining 

 three days at the temperature of the laboratory (about 18° C.) a few 

 of the conidia had germinated. They showed no appreciable increase 

 in size before the protrusion of the germ tubes. The latter were at 

 this stage one to four times the length of a conidium and frequently 

 were more or less geniculate; they emerged laterally, sometimes at 

 or near the middle of the conidium, at others more towards one or the 

 other extremity, but none was seen truly polar. 



In June of the same year (1914) Mr F. J. Chittenden sent us a 

 specimen of the Fig "canker" from the glass-houses at Wisley; this 

 bore pycnidia and conidia similar to those described above. 



The pycnidial form of fructification and the spore-characters referred 

 the fungus to the genus Phoma, and reference to Saccardo's Sylloge 

 Fungorum enabled us to identify it with P. cinerescens Sacc. in 

 Mich. I, p. 521 (1879). The specific diagnosis given is as follows : " Peri- 

 theciis gregariis, globoso-depressis, atrolivaceis, subcutaneis; sporuUs 



1—2 



