72 
M. Cheveley Ray net*. 
to place the axis in a vertical position. For comparison with these 
sterile seedlings, there are shown, in Text-fig. 1, two seedlings 
(G, H) germinated in moist air from unsterilized seeds and 
infected with mycorhiza. 
Text-fig. 1. Seedlings of Calluna vulgaris. A to F, sterile seedlings ger¬ 
minated under aseptic conditions on agar plates. (A to C, four weeks after 
sowing ; D to F, eight weeks after sowing). G and H, seedlings germinated 
in moist air, seeds unsterilized, seedlings infected with mycorhiza ; eight weeks 
after sowing. All x 12. 
The tube shown in Text-fig. 2 is used for sand cultures; with 
slight modification similar tubes can be used, without filters, for 
water or agar cultures. After filling the sterilized tubes with agar 
media or with fine quartz sand as the case may be, the latter 
washed and sterilized in the usual way, the whole apparatus is 
sterilized again and when cool, is ready for planting. 
After placing the filters in the solutions, the sand at the 
surface becomes moist, from capillary rise of the solutions, in about 
three hours. 
The seedlings can be rapidly transferred to the tubes and the 
covers replaced. By filling the shoulder S with sterilized sand, the 
tubes can be manipulated without risk of knocking off the covers 
after sterilizing, and by moistening this sand with sterile water, a 
