180 HETEROGENETIC ORIGIN OF 



had become hard and was of a slightly brownish colour from the 

 action of the formalin. Microscopical examination of the more 

 peripheral parts of the orange also showed no mycelial filaments 

 or organisms of any kind. 



The other orange in the same bottle showed no organisms, either 

 to the naked eye or on microscopical examination. 



Soon afterwards, two other Tangerine oranges were treated in 

 the same way and subjected to similar conditions, except that they 

 were left in the bottle for a much longer period — that is, for five and 

 a half weeks instead of only fifteen days. About five days before 

 the bottle was opened one of the oranges was seen to show a patch 

 of dark colour on one side, and when it was subsequently cut open 

 longitudinally all the central white tissue was found to present an 

 altered appearance, being of a rather dirty white colour ; and on 

 microscopical examination it was found to be densely infiltrated 

 with a delicate Fungus mycelium. The seeds were discoloured, 

 and the mycelium was also found to extend into the yellow 

 substance of the orange. In one place there was a patch of a 

 blackish colour, and this was found to have grown into the rind of 

 the orange at the point where the discolouration on the surface 

 was seen. It had not, however, actually reached the external 

 surface, it had evidently grown from within outwards, and the 

 surface of the orange, here and elsewhere, showed no trace of 

 Mould of any kind. 



The companion orange again showed no organisms either 

 internally or externally. 



There is no means of accounting for Mould springing up in the 

 interior of an orange by infection from without. In a memoir 

 entitled " Recherches sur la pourriture des fruits " ' Davaine 

 points out that in fruits, such as the apple, the pear and the medlar 

 in which there is an open calyx, " le tube calicinal peut conduire 

 les spores ou leurs filaments jusqu'au centre du fruit. C'est ainsi 

 que se produit le blettisemenl,^ qui n'est autre chose qu'une 

 pourriture ; " but the process of rotting, he says, is always external 

 " chez les fruits qui sont partout reconverts d'un epiderme, tels 

 que le citron, I'orange, et les fruits a noyau." 



■ " Corapt. Rend.," 1866, pp. 277 and 344. 



' That is, the mellowing process that occurs in pears and medlars more 

 especially. Further on in his paper Davaine says he has " recently recognised 

 that this latter (bldtiscment) may take place where spores are excluded, and in 

 the absence of any mycelium.'' 



