52 THE ORCHID REVIEW. 
stages, on Dendrobium and Oncidium, in the Laboratory at Kew, by Mr. 
Massee, so that if once introduced it might prove troublesome. In the 
Seychelles it caused much damage, hundreds of pods damping off, doubt- 
less through their food supply being cut off owing to the damage to the 
leaves caused by the fungus. The fungus grows much in the same way as 
the preceding, the spores germinating and entering the tissues through the 
stomata, and there producing a mass of mycelia in: great abundance under 
the epidermis. About the time that the leaf is killed the fungus enters a 
new stage. The mycelia cross, lateral branches are given off, which become 
closely entangled and eventually form a small colourless cushion, which 
bulges up the cuticle and bursts through, producing pale yellow agglutinated 
masses of gonidia on the upper surface of the leaf. At a later stage these 
gonidia produce perithecia containing spores, which completes the life 
history of the organism. Formerly these three stages were considered to 
represent distinct fungi, belonging to different genera, and the two latter 
were supposed to be saprophytes, only living upon decaying matter when 
the first had done the mischief. This idea is embodied in the most recent 
articles on the subject, but, as we have seen, is erroneous. In fact, the 
second and third are practically the flowering and fruiting stages of the 
fungus. 
A few words must be said as to preventative measures, and here we see 
the importance of knowing the life history and habits of the enemy. Instead 
of the disease being caused by some fungus which propagates itself nobody 
knows how, and being followed by some harmless saprophytes, these 
innocents are seen to be the very root of the mischief. Extirpate them, root 
and branch; burn every fragment as soon as found, and the disease will 
cease from troubling. These very measures have proved effectual in checking 
the Vanilla disease in the Seychelles. Again, it was on a piece of damp, 
insufficiently drained land that it originally appeared, and this is also sug- 
gestive. Keep the houses properly ventilated, and avoid a too moist stagnant 
atmosphere, and thus check its development by hygienic means. There may 
be cases where a weak solution of sulphate of copper could be used with 
advantage, but the former remedies will probably prove effectual. 
Very little is yet known of the fungi which affect Orchids, and some ot 
these if introduced might give little trouble, though one can never become 
surety for their good behaviour. The Vanilla disease was probably intro- 
duced from America, where it has been observed, but nothing seems to be- 
known of the native country of Cladosporium Orchidearum. It is desirable, 
however, that these blanks should be filled up, and examples of fungi on 
leaves of Orchids, either wild or cultivated, would be useful as a means of 
ee our — of the subject. 
2a 
