135 



passed. Some of these spores are broken, but no greater pro- 

 portion than before ingestion. The breakage is due to the 

 treatment with the sieve. Even the microspores appear in 

 the excrement apparently unaltered. In the same manner 

 the aerial conidia of this fungus collected in water slightly 

 sweetened may be fed to flies with the result that they pass 

 through the alimentary canal unaltered. 



All these spores germinate readily after passing through the 

 canal of the tiies. It appears to make little difference what 

 fiy is used so long as it is a species that is accustomed to 

 seek saccharine fluids as food, or is omnivorous and accus- 

 tomed to saccharine food. In all such cases the spores, if 

 passed through the fly in what seems to be the normal way, 

 will germinate afterwards. If the fly has a ^ood supply of 

 food, in other words, all that is desired, the passage of the 

 food through the most common species requires only a short 

 time. The principle of the fly's digestive economy seems to 

 be the use of large quantities of food and the absorption of 

 only what is readily soluble. Thus, in the case of spores 

 placed in sweetened water, only the saccharine matter is ab- 

 sorbed. The spores, even when they are rather frail and thin- 

 w^ailed, suffer little if any diminution in vitality by passage 

 through the fly. The consequences of the general statement thus 

 made are almost beyond conception. The relations of flies, not 

 only to the pineapple disease, but to diseases of all sorts, is thus 

 shoum to be of the very greatest importance. 



The location of the pineapple rot is largely determined bv 

 insects, and its spread from one plant to another is largelv the 

 result of insect work. The mealy bug, as it is called, of the 

 pineapple naturally seeks protected places where it can find 

 food of the right nature. The protected places are the lower 

 angles between the carpels on the lower part of the fruit and 

 beneath the lower leaves of the top. At these points it seeks 

 out the tender places where it can insert its proboscis for th? 

 purpose of sucking up its food. As the fruit erows there is 

 a gradual opening out of the angle between the carpels by 

 which new epidermis not hitherto exposed comes to the light 

 and air. It is through this tender epidermis that the insect 

 prefers to insert its proboscis. At the apex of the fruit, just below 

 the lower leaves of the top, is another location where the in- 

 sect finds similar congenial conditions. The location of the 

 insect determines to a considerable extent the cra'^king of the 

 fruit, and it is through the cracks following on the results of 

 the insects' punctures that the rot finds an entrance. Hence 

 the rot is most common at the base of the fruit and at the 

 top. Occasionally the blossom end of a carpel will be sufli- 



