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METHODS IN PLANT HISTOLOGY 
trying to get Saprolegnia or Achlya. The fixing and staining de¬ 
scribed for Saprolegnia will give good results with the other genera. 
Albugo.—This fungus is quite common on Cruciferae, where the 
white “blisters” or “white rust,” Albugo Candida, form quite con¬ 
spicuous patches. Affected portions of leaves and stems should be 
fixed in chromo-acetic acid and cut in paraffin. Sections 5 m or less 
Fig. 55.— Albugo Candida: A, small portion of a section of a blister showing coenocytic 
mycelium, conidiophores, and multinucleate conidia; B, a young oogonium with large coenocentrum 
and many nuclei: C, later stage, after differentiation into a central ooplasm, surrounded by the multi¬ 
nucleate periplasm; all of the nuclei of the ooplasm, except one, have disorganized. Fixed in the 
special chromo-acetic acid solution and stained in iron-alum haematoxylin and orange. X780. 
in thickness will be found most satisfactory. Stain in iron-alum 
and counter-stain lightly with orange (Fig. 55). 
The white blisters cause little distortion, but are easily recognized 
by their color; the oogonia do not cause any change in color, but they 
cause great distortion in the pods or stems, so that these organs may 
reach several times their normal size. Parts only slightly distorted 
should be selected, as well as the extreme cases; otherwise, you will 
