17 



appear red and in another green. Similar appearances may be seen 

 in other forms of G-loeosporium, but they are not usually so marked 

 as in the Gloeosporium of the guava. 



If, now, other fruits be inoculated with these spores, as grown on the 

 guava, strong growths will be secured that present certain variations. 

 In most instances (banana, apple, quince, pear) the spores contain 



X400 



Fig. 41. Spores of the 

 Gloeosporium found 

 growing naturally on 

 the fruit of the guava. 

 Compare these origi- 

 nal spores with their 

 progeny shown in 

 Figs. 40, 42, 43, and 

 44. 



X400 



Fig. 42. Spores of the 

 Gloeosporium obtain- 

 ed from inoculating a 

 pear with spores of 

 the Gloeosporium 

 found growing natur- 

 ally on the guava. 

 Compare this with 

 adjacent figures. 



X 400 



Fie. 43. Gloeosporium 

 spores obtained from 

 an inoculation on 

 quince with spores 

 from the Gloeospor- 

 ium found growing 

 naturally on the 

 guava. Compare this 

 with adjacent figures. 



X400 



Fig. 44. Gloeosporium 

 spores obtained by 

 inoculating a banana 

 with Gloeosporium 

 spores found growing 

 naturally on the 

 guava. Compare these 

 with Figs. 40-43. 



finer granules and a more distinct vacuole. This is distinctly noticeable 

 on the pomaceous fruits (see Figs. 40 to 44). Now, as the Gloeosporium 

 ordinarily found on pomaceous fruits is more finely granular than the 

 form seen by me on the guava and used in these observations, we may 

 safely suspect that the guava Gloeosporium, when grown on the 

 pomaceous fruits, varies in the direction of the form characteristic of 

 those fruits. It is needless to point out that this is what we should 

 expect if one of these Gloeosporia is a derivative of the other, and too 

 closely related to be regarded as specifically distinct. 



As to the variations in the size and form of the spores of fungi, we 

 see in the measurements resulting from the inoculations already 

 recorded what large variations may occur as the result of varying 

 environment, such as is afforded by the various fruits employed. We 

 may have spores varying in size from 5 x 7/u. to 6 x 18/u,., and in form from 

 nearly round through ellipsoidal and elongated to clavate. If any 

 attempt had been made to secure extremes, it would have been easily 

 possible to have exceeded the limits of size and form here set down. 



A thoughtful review of the various colours displayed by the diseased 

 spots resulting from the attacks of a given form of Gloeosporium on 

 a variety of fruits will, I think, result in the opinion that these colours 

 are in harmony with the physiological functions of the host, and I am 

 sure that to a less extent the same is true of the colour and form of 

 the pustules and spores. Thus the colour of the fruit itself enters 

 to some extent into that of the diseased area, and the chemical 

 reactions of the fruit's constituents have a decided influence on the 

 colour of the rot. Some varieties of pears have a tendency to blacken 

 the pustules of the fungus. Turning to the form of the spores, 

 nothing could be plainer than that the peculiar epidermis of certain 

 fruits, through its extra resistance to rupture, gives a peculiar irregu- 



36567 B 



