ON A TECULIAE X'ORM OF MILDEW IN ONIONS 95 



tion was visible in the portion of tlie mycelium which was situated 

 Avithin the drop of water. That moulds when growing in water 

 not only present great differences as to their mycelium, but even 

 as to fructification, appears from the various observations M'hicli 

 refer such states to Algoe, or to distinct genera of mucedines and 

 mucorini. Aelilya iwolifera, respecting which linger* has made 

 such curious observations, is probably a mere anamorphosis of 

 some" mould, or if not so, it is at least an aquatic species, and so 

 far anomalous, though scarcely more so than the Algerian 

 Sphcsria Posidonice, Montagne and Durieu, which grows on 

 the shoots of Posidoiiia when yet remaining on their marine 

 bed, and constantly covered by the sea, and is a very highly de- 

 veloped species. 



A curious observation was made in the autumn of 1846 by 

 Mr. Hoffinan on a mycelium with which the interior of a decay- 

 ing pear was impregnated. It should be mentioned first, that 

 during that autumn the leaves of many Apple and Pear trees at 

 Margate were covered with a white flocculent fungus, which 

 was, however, never seen in fruit. All the fruit of these parti- 

 cular trees rotted ; and though no fungus appeared externally, 

 the cells of the fruit exhibited very clearly a jointed mycelium. 

 An extremely minute portion of this, cleared as much as pos- 

 sible from the cellular substance of the matrix, was subjected 

 to precisel)' the same treatment as that observed in the ex- 

 amination of the onion mildew. It shortly began to grow 

 and spread in all directions, but so long as it was confined 

 to the fluid no normal fructification appeared ; the articulations 

 of the threads, however, contained oblong-elliptic grains, 

 which were soon dispersed in the fluid, after the fashion of 

 the reproductive bodies in Bryopsis and some Confervce. 

 They possessed at first a slight molecular motion, which soon 

 subsided ; and M'hen they became stationary they germinated, 

 and gave rise to jointed threads, similar to those of the parent 

 mycelium. As soon, however, as the flocci penetrated into the 

 surrounding air, a very different sort of fi-uctification appeared, 

 by which the mould was easily recognised as Penicilliuvi can- 

 didum, Grev. The true spores were of the same form and 

 size as those which had been developed M'ithin the threads in 

 water, and it should be observed that no external fruit had ap- 

 peared when tlie grains of the joints were first dispersed, or even 

 till after tliey had germinated. Precisely the same results were 

 exhibited in a second experiment. It was found afterwards that, 

 even in situ, as might be expected from the abundant moisture 

 of the decayed fruit, the reproductive granules were produced 



* Limiffia, vol. xvii. p. 129. 



