size more than was the case where they found an easy exit. In 

 some instances I observed that pustules which at first showed these 

 traits of irregularity would, after the rupture of the epidermis, assume 

 greater regularity as a result of this release of pressure. 



The colour and internal structure of the spores were less variable 

 than the form, but even these were subject to decided variations. 

 Thus in the case of the Gloeosporium of the guava, a form with large 

 and loose internal granulation, it was evident that when grown on the 

 pomaceous fruits its granulation became finer, and in the same 

 connection the vacuole became more definite in form. The variations 

 in colour, however, seemed comparatively slight. 



I must add that it is not entirely to mechanical causes that I 

 attribute the resistance of the skin in certain cases to the action of the 

 fungus. I feel it all the more necessary to mention this because my 

 conclusions in another somewhat 

 similar case appear to me to have 

 been misunderstood. It may be 

 true, and I think probably is 

 true, that fungi at the time of 



their outbreak exert a chemical 7 ._ Ripe . rot spores geminat ing. 



effect upon the epidermal tissues 



of the host, perhaps a solvent effect. But whatever means may be 

 utilised by the fungus to effect its release, it seems to me the effect 

 on the parasite of an enforced delay in the outbreak will be much the 

 same. It will go on increasing in size, and this growth will result 

 in the pressure which has been mentioned above. 



It would not be unreasonable to suppose that there would be 

 connected with a mechanical toughness of the cuticle an internal 

 resistance to the attacks of the fungus due to a correlated toughness 

 of parenchymatous tissues. There is evidence of such correlation in 

 a number of fruits. 



Description of Various Inoculation Experiments. 



I have now to add to the cross inoculations already mentioned the 

 following more recently made by me in connection with the occurrence 

 of the ripe-rot on the passion-fruit and other fruits. 



2. PASSION-FRUIT inoculated from Guava 

 Gloeosporium. After eighteen days there 

 was no tangible result. 



1. PASSION-FRUIT inoculated from the 

 Gloeosporium of the Banana. The inocula- 

 tion point became the centre of a dis- 

 coloured area, which in the course of 

 three weeks became nearly an inch in 

 diameter. No pustules appeared. It re- 

 mained undetermined whether the exciting 

 cause was Gloeosporium or not ; but I am 

 inclined to think it was the Gloeosporium. 

 There is a Gloeosporium occurring in nature 

 on the passion-fruit, the fnrm of whose 



rres it is impossible to distinguish from 

 se of tne species known as Gloeosporium 

 fructigemim, although I failed on taking 

 these spores and testing them by inocula- 

 tion to prove that they would infect other 

 fruit. Only one series of trials was made. 



3. LEMON inoculated from Gloeosporium 

 of the Banana. In a week there was 

 definite proof of disease in the shape of a 

 discoloured area concentric with the inocu- 

 lation spot. This area continued to increase 

 slowly in size for six weeks, the lemon 

 meanwhile becoming dry and hard. It 

 seemed as if the skin of the lemon became 

 too tough to allow of the fungus forming 

 pustules. It remained undetermined whe- 

 ther the fungus resulting from inoculation 

 was really a Gloeosporium, but I am inclined 

 to think it was, and that in all probability 





