430 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



area of discolouration showed the hypha? ramifying in and among the 

 cells, and the whole leaf between the apex and a little below the point of 

 infection was permeated with the hyphae and killed. The pycnidia first 

 appear some three weeks after sowing. 



I have frequently produced this disease at definite spots by artificial 

 inoculation from the spore, the disease appearing only at the place where 

 the spores have been sown. 



In rainy weather drops of water collect upon the leaves, especially at 

 any bend of the surface and at the axils, and it is just at such places 

 that the fungus is ordinarily to be found. Artificial infection can easily 

 be effected by sowing the spores in a drop of water thus naturally 



Fig. 116. — Cells from the epidermis of Carnation leaf upon which a spore has germinated. 

 The germ-tube is seen entering a stoma. A. spores. Zeiss Obj. D, Oc. 4. 



collected upon the leaf. In young leaves, however, water will not 

 readily lie upon the surface, but if the bloom is rubbed off* by gently 

 brushing with a wet camel-hair pencil a drop of water will then adhere 

 to the leaf in which the spores can be sown. 



My infections were made, with material brought from Warwickshire, 

 upon plants in my own greenhouse in Newcastle ; and it is quite clear 

 that the disease is very readily communicable from one plant to another. 

 It has wrought considerable havoc in the old garden from which I first 

 obtained my specimens, but so far I have not found it in any other 

 locality in England. This fungus causes great damage to Carnations in 

 North America, and is also known as a troublesome pest in Europe 

 (especially France, Italy, and Portugal), South Africa, and Australia. 



