PLANT DISEASES AND FUNGI. 21 



to the attacks of insects, of various kinds, which it is the province of 

 the entomologist to investigate. Undoubtedly, the attention of 

 farmers, and others interested in agriculture, was directed to insect 

 pests for years before the slightest effort was made to check the 

 ravages of fungoid parasites, and even before fungi were reckoned 

 as a factor at all in the production of disease in crops. 



In addition to these two causes, the most common and most 

 injurious, there are other subsidiary elements which tend to disease, 

 such as bad cultivation, insufficient drainage, overcrowding, uncon- 

 genial soil, impure air, external injuries, and, as we believe, hereditary 

 transmission. Of all these, our remarks are intended to apply to 

 diseases having a fungoid origin. 



It has been objected by some writers that fungus diseases are in 

 no sense hereditary, but are communicated externally to each 

 generation of young plants, and therefore when infection is provided 

 against, all that is necessary has been done. This we hold to be a 

 dangerous deception in the face of the following facts : " A well- 

 known nurseryman, in a large way of business, had imported seeds of 

 Dianthus direct from Japan. These seeds were carefully grown 

 under glass, and, immediately they were up in the seed pans, they 

 were all attacked and destroyed by Puccinia lychnidearum. On 

 making a microscopical examination of a series of the seeds, 

 mycelium was detected inside the integument which surrounded the 

 embryo, or infant plant, and within the coat of the seed."^ It may 

 be explained that the mycelium is the first stage in the development 

 of fungus disease, and consists, for the most part, of the slender 

 delicate filaments which result from the germination of fungus spores, 

 or from the rejuvenation of portions of a hybernating or perennial 

 mycelium. 



Many years ago we were consulted on the condition of certain 

 celery plants in a garden at Hampstead. Two or three rows of 

 plants were in a perfectly clean and healthy condition ; but one or 

 two rows of plants growing beside them were covered with pustules 

 of the celery brand, Puccinia apii, and thoroughly useless. Upon 

 inquiry we found that the healthy plants had been raised from an 

 old stock of " saved " seed ; whereas the diseased plants had been 

 raised from other seed which the gardener had begged from a friend, 

 because his own seed was insufficient for planting all the ground he 

 wished to cover. All the diseased plants were at once rooted up 



3 " Gardener's Chronicle," 26th January, 1884. 



