48 THE ORCHID REVIEW. [Mar.-APRIL, 1920+ 
unthinkable, but to have the blinds fixed ready for use, if necessary, is 2 
wise precaution. It may be that a sudden burst of sun, with possibly 
unavoidable fire-heat, will send the temperature inside racing up, and this | 
is when restraint in ventilating should be exercised ; and on windy days 
enough air will find its way into most. houses without the necessity of 
opening the ventilators at all. 
_A sudden rise of temperature caused by sun heat in sik is not nite 
to be afraid of, and no attempt should be made to blow it out. Little 
stability of temperature can be hoped for, nor must we attempt to .modify 
it too severely by ventilation so early in the year. The constancy of the 
night temperature is of more moment, and is easy of attainment. _ 
But I would venture to say that temperature has very little to do with 
leaves in healthy plants becoming prematurely yellow in the early spring. 
Too much air admitted at this season—though the temperature remain. well 
up—suggests itself as the cause, helped no doubt by fitful periods. of bright- 
ness without direct sunshine. Such plants as Tomatoes and Geraniums, 
when removed frém the ‘coolest quarters inside and stood. outside, quickly 
lose some of their lower leaves, those furthest from the growing point, which 
otherwise they would have long retained. In opening the top and bottom 
ventilators of an Orchid house the accustomed moisture is removed from 
the plants, and the leaves furthest from the lead or growing point now throw 
offthe moisture at an accelerated rate, and thesupply is too slowly replaced, 
and consequently they begin to wither.. With the longer light there is 
little doubt that the plants steadily adapt themselves to the airier conditions, 
and what had during the winter-become a kind of stagnant condition of the 
back or dormant’ parts of the plants—with the relatively close conditions 
imposed upon them during’ the: short days—now get.a quicker supply of 
sap, and are able to replace all that, is required of thém. Some such 
explanation must be found for the very sensitive condition of the leaves on 
the back bulbs in the early months when the sun begins to get power, but 
the precautions to be. taken are simple when we realize the necessity for 
them. ce ae: } Te J. M. Brack. 
Sune Wasps IN ROLLER Basins Thinking you may be acidaed. 
I send particulars of a fine haul of queen wasps, secured on my premises 
during March. We have captured 130; they had hibernated in the lath 
- blinds on'the northern side of the Odontoglossum houses, these blinds not 
having been unrolled since used last antumn,.and on the first’ day of being 
unrolled the wasps were captured. No doubt the small amount of escaping 
warmth from the roof and. the comparatively dry position had attracted 
them, and I bring this to your notice in order that others way be on the 
look-out for similar hauls.—A. McBEan. 
