Apri, 1909. | THE ORCHID REVIEW. 111 
the right place is found for them, and a little care taken with watering in the 
winter months. Theyshould not be syringed so heavily or watered as much 
as other Cypripedes, nor do they need so heavy a shading. A similar 
shading to that used for Cattleyas will suit them, and plenty of air during 
the summer months. 
DAMPING DOWN must be done frequently, or thrip will soon become a 
nuisance; it also helps to keep the pots from drying so rapidly. Walls and 
pathways should be thoroughly saturated during the hot weather. 
VENTILATION.—Houses can be more freely ventilated after March is out, 
as we do not get such keen winds, but care must be taken not to chill the 
houses. Commence early in the morning with a little air, and not leave the 
houses shut up until they get hot and then put a lot on, as a sudden check 
is more harmful than too much heat. 
TEMPERATURES should be kept as even as possible at night, allowing 
enough fire heat to maintain the proper figures. These should run about as 
follows at night : Stove or East Indian House, 70°; Cattleya house, 65°; 
Intermediate house, 60°; Odontoglossum house, 55°. Allow from 5° to 
10° rise during the day time, the latter when sun heat is available, but at 
other times the former will suffice. 
LEAF-SPOT OF ODONTOGLOSSUM UROSKINNERI. 
AN interesting and important account of the well-known spot-disease of 
Odontoglossum Uroskinneri, by Mr. M. C. Potter, M.A., F.L.S., has just 
appeared (Gard. Chron., 1909, i. pp. 145, 146, fig. 62-65). After describing 
the appearance of the affected leaf, and its microscopical structure, Mr. 
Potter remarks: ‘In the leaf-spot of Odontoglossum there was no sign of 
any fungus to be found. But special staining and examination under a 
high power of the microscope revealed the presence of numerous bacteria. 
These occupied notably the cells surrounding the tissues in the initial stages 
of gum formation, and could be seen almost filling the cavity of the cells. 
Although the subject requires further investigation, it is probable that these 
bacteria have some destructive action upon the protoplasts, and that from 
this action results the escape of the cell contents, and their conversion into 
the gummy substance, filling up the intercellular spaces. 
** Attempts have been made to induce the disease upon healthy plants 
by inoculation with bacteria isolated from the diseased leaves, but have been 
unsuccessful. Ii must be remembered, however, that infection is often 
critical and uncertain, and depends upon conditions sometimes difficult to 
approximate. It has been noted that the spot is more prevalent when 
the plant is grown in a very moist or almost saturated atmosphere, and 
in such conditions it is very liable to spread. In a dry atmosphere, on the 
