Schwartz.—Parasitic Root Diseases of the ftmeaceae, 513 
Folkestone beds (Lower Greensand) with the Gault. Here the water and 
the rich alluvial soil were highly charged with iron salts dissolved by the 
former in its passage through the Greensand ; the situation also was more 
shaded than the spot where I had commenced my search, and an altogether 
more favourable one for the presence of diseased plants. J. bufonius , 
articulatus , and lamprocarpus were very common, but plants of the first- 
named were very free from tubercles, about one in three hundred being 
diseased, although plants of the two latter species growing with them were 
in almost every case diseased, many possessing large tubercles, whereas 
those found on diseased bufonius plants were mostly small and insignificant. 
This comparative immunity of the bufonius plants might perhaps be ac¬ 
counted for by the fact that J. articulatus and J. lamprocarpus are perennial 
plants, whereas J. bufonius is an annual; nevertheless, it is difficult to see 
how this could afford a true explanation, as the ditches are cleaned out every 
year, and most of the perennial plants are quite young if not. first-year 
plants ; the roots, however, of the perennial plants contain large quantities 
of reserve starch, which is lacking in those of the annual bufonius plants. 
It would seem probable, therefore, that J. bufonius is more resistant to the 
disease, and has perhaps undergone some protective evolution against it. 
I have laid stress on the soil and situation in which I found the 
diseased plants, as these are important factors, and largely determine the 
question as to the presence or absence of disease. Thus, for instance, it has 
been stated that Sorosphaera Veronicae is of very rare occurrence, but this 
is by no means the case if the search for diseased Veronicas is limited to 
those growing in damp shady situations. A sunny situation is apparently 
inimical to the presence of disease, or it is one in which plants are sufficiently 
robust to resist attack by parasitic fungi. 
The material gathered was fixed in the field in Bouin’s fixing fluid 
made up according to the formula:— 
Crystallizable Acetic Acid, 2 c.c. 
Formol, 10 c.c. 
Aqueous solution Picric Acid (saturated), 30 c.c. 
The picric acid was afterwards removed by repeated washings in 
50 per cent, alcohol. Absolute alcohol and Flemming’s solution were also 
tried as fixing agents. 
Sections were cut with the microtome, and various stains used, the best 
results obtained being with Benda’s Iron Haematoxylin. In the case of 
those plants gathered in the vicinity of the Folkestone beds it was possible 
to dispense with the use of the iron solution, as the roots had been 
already thoroughly impregnated in their habitat. Ehrlich’s Haematoxylin 
and Flemming’s triple stain were used in a few cases. Many of the smaller 
thin diseased roots were not suitable for sectionizing, but stained, teased- 
