72 



entirely of loosely aggregated dark-coloured, sub-spherical cells. 

 These occurred in groups of from four to several scores. 



On being subjected to water culture in an infusion of lemon-peel, 

 these cells gave rise to a vast multitude of yeast-like conidia, which 

 fell off and continued to bud and separate like yeast, yet without the 

 formation of chains and with a rapid diminution in size. Each of 

 these conidia had one or two vacuoles. The phenomena closely 

 paralleled those recounted by me for the similar fungus found con- 

 nected with the scab of lemon bark (Vol. VI, p. 865, Agricultural 

 Gazette) . 



Beside producing these yeast-like conidia, the cells of the Conior 

 thecium gave rise to colourless mycelial threads, divided by septa into 

 cells two to six or eight times as long as broad. 



BLACK SPOT OF THE CITRUS ERUITS. 



IT is not at all unfrequent to hear it said that this disease spreads from 

 one fruit to another, and that it develops and spreads in the cases 

 of fruit after they are placed in storage. Some observations and 

 experiments lead me to the conclusion tliat there may be gome miscon- 

 ception about this. 



The spores of this- disease do not readily germinate under the 

 laboratory conditions ordinarily brought to bear in tlieir examination, 

 and in this respect they differ from most spores found in connection 

 with prevalent fungus diseases. The following observations, though 

 they are inconclusive, are inserted here out of regard to the rarity with 

 which I have observed these spores to germinate : 



Spores of this fungus were ringed in, with a small supply, of water 

 and numerous air bubbles. The spores, which were entirely like those 



figured in " Letters on the Diseases of 

 Plants/' Agric, Gaz., vol. V^II, p. 230, after 

 twenty-four hours had failed to germinate in 

 tnose P arts wnere tne y were completely -sur- 



in water-culture, rounded by water. Spores located 1 -at 5 '-'the 



giving rise to a remarkably fine -. i r 7 , , , , f . -, . , r , 



mycelium. edges of air bubbles where on one side they 



had access to air, each sent out into the air 



a single very fine unbranched mycelial thread about 6ne micromillimetre 

 wide, though slightly wider at the free end. The mycelium was colour- 

 less, and so fine as, under the circumstances, to preclude observation 

 as to septa ; none were seen. At the end of twenty-four hours the 

 length of these hyphae averaged several times the length of the 

 spores. 



As to the spread of the Black Spot disease a'mong citrus fruit in 

 store, the following observation may be of interest : 



A ripe lemon that presented a pronounced case of this disease was 

 utilised to test its communic ability. Spores were removed from a 

 well-developed pustule and inoculated into a healthy portion of the 

 Tind of the same lemon. It was thought if the disease spread on fruit 

 in store, as sometimes claimed, this inoculation ought to give a 

 positive result. Two inoculations were made, but neither gave any 



