102 



elements, 7*2 1 I/A in diameter, and variously grouped and grown 

 together. The appearance of the fungus is similar to that found in 

 the lemon scab. 



In a water culture after twenty-four hours the above mycelium gives 

 rise to colourless septate hyphsD, which in turn produce conidia that 

 bud after the manner of yeast. 



What seems beyond doubt the same fungus occurs on the leaves, 

 but the spherical elements are grouped into larger communities. 

 While on the fruit the rule is two to six or eight together, on the 

 leaves the groups are composed of twelve to twenty elements. The 

 aggregations on the leaves are also of a darker colour. 



Another difference noted was the occurrence on the leaves of a 

 mycelium of the ordinary form, composed of cells one to one and 

 one-half times as long as wide. This mycelium was of about the same 

 colour as the spherical elements of the Coniothecium. Very little of 

 such mycelium was to be seen on the berries. Whencesoever 

 derived, this mycelium had the property in water cultures of proli- 

 ferating in the form of colourless threads, septate, and composed of 

 cells one and a half to two times as long as wide. This mycelium, 

 as well as the elements of the Coniothecium form, has the power to 

 produce conidia that bud after the manner of yeast. 



The spherical elements in the growth on the leaves are somewhat 

 smaller than indicated by the measurements given above (7*2 x 1.1/n). 

 The differences are shown in the illustrations. 



X400 



Fig. 120. Cultivations of the fungus found 

 growing on the leaves of Crataegus, 

 forming there a kind of black incrusta- 

 tion ; a, dark mycelium made up of some- 

 what elongated cells ; 6, transparent 

 colourless mycelium, appearing in the 

 water-culture ; c, yeast-like cells de- 

 tached from b, and growing by a budding 

 process ; d, a piece somewhat similar to 

 a ; e, detached mycelium resembling 6, 

 which is not yet detached ; /, mycelium 

 composed of sub-spherical nearly black 

 cells, and comprising much of the sooty 

 growth on the Cratsegus or Hawthorn 

 leaves. 



It will be noticed that the Hawthorn-hedge pests enumerated as 

 having come under notice are either identical with those known to 

 infest the apple, pear, and other pomes, or are very similar to them. 

 This is a sufficient proof that an infested hedge is a source of danger 

 to orchards. Under the circumstances it would seem to be a wise 

 precaution to spray such hedges when spraying the orchard. This 

 will at the same time improve the hedge. If the hedge underwent the 

 winter treatment with lime, sulphur, and salt, that would also be a 

 benefit. 



This matter is mentioned here on account of the author's knowledge 

 of the existence of a number of infested hedges near orchards. 



