478 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



confessed that our knowledge of the occurrence and distribution of 

 these minute fungi upon wild plants is very incomplete. It would 

 be a useful and interesting piece of work for anyone with the requisite 

 technical knowledge and leisure to ascertain precisely to what extent 

 the fungi which attack our cultivated plants will infect their wild allies, 

 and vice versa. Microscopical examination alone is unfortunately 

 not to be rehed upon, and may actually be misleading, for we have 

 to reckon with two very curious phenomena in the physiology of 

 fungi — polymorphism, and the perhaps even more strange case where 

 morphologically similar fungi are restricted in their range of infective 

 capacity, and cannot indiscriminately attack any variety even of 

 one species. Only carefully conducted and controlled cultural and 

 infection experiments are likely to give rehable evidence." 



Although the variety Apii of the fungus has not been recorded 

 on wild plants, there is a record of a species, Septoria Petroselini forma 

 segetum P. Brun, occurring on the leaves of Petroselinum segetum in 

 France. The spores of this form are 30-50 X i /x. It would be inter- 

 esting to see what would be the result of trying to infect cultivated 

 celery with this fungus. 



In the summer of 1913, while cycHng along the coast road of 

 Ballyconneely Bay, a very remote spot in West Galway, I noticed a 

 considerable clump of what appeared to be wild celery in full flower. 

 Being in the company of a fellow botanist, we called a halt to examine 

 the plants, in order to ascertain that they really were celery plants, 

 for although the district was fairly well known to me I had never 

 seen the wild celery in it previously. The plants certainly were what 

 we at first guessed them to be, and evidently the colony was an old- 

 established one. 



On looking up the distribution of this plant in Ireland as given 

 in Praeger's " Irish Topographical Botany," it was found that, 

 although it occurs locally round almost the whole coast of Ireland, its 

 presence had not been recorded for the division West Galway. Hence 

 its discovery there links up the distribution of the plant in the South- 

 East Galway division with that in the West Mayo division. 



On examining the plants it was noticed that the foHage was con- 

 siderably spotted with rounded, dead areas, on some of which were 

 a few minute black bodies suggesting pycnidia. The opinion was 

 hazarded, more- perhaps as a jest than anything else, that here was 

 the cultivated celery disease on the wild celery ! 



Certainly the macroscopic appearances were rather against the 

 suggestion. The spots on the leaves were seldom, if ever, confluent ; 

 they were relatively small, and they retained their form and individual- 

 ity even on old leaves which were apparently otherwise dying a natural 

 death. There was no appearance of a general decay of the leaves 

 caused by the presence of the fungus, such as occurs in the case of 

 the cultivated celery : and furthermore the numbers of pycnidia on 

 the diseased areas were very small, generally only one or two, and 

 frequently none at all. 



