1895.] Root Tubercles of Leguminosae. 901 
appeared. These stained faintly with ordinary reagents, but 
distinct round bodies appeared in their interior when they 
were subjected to the spore stain. In sediment IV, no bacilli 
were found, but there were small stained bodies which might 
well be spores, and plate cultures gave numerous colonies. 
The plate cultures from these sediments yielded unquestion- 
able B. tuberigenus 1, 2,3. The remaining forms appeared to 
be ordinary soil bacteria, and were not followed further. 
From the results of these cultures and the examination of a 
great many cover glass preparations, the author thinks it is 
established that the tubercle organisms pass the winter in the 
earth in the form of spores. Sand cultures and infections were 
made at Rostock and again at Danzig, the following method 
being employed. The sand was spread out in an oven and 
heated for five hours at 150° C. It was then put into 3-litre 
pots, previously washed many times in boiling distilled water, 
then several times in 1-500 solution of mercuric chloride, and 
finally in sterile water. The pots were then covered tightly 
with sterile cotton and set aside. Subsequently they were in- 
fected with organisms directly from the tubercles and also with 
pure cultures of the same. In the Rostock experiments the 
pots were watered with Frank’s salt mixture and in the others 
they received only sterile water, bacteria being added from 
time to time to each watering fluid. The seeds planted in 
these pots were first soaked ten minutes in 1-500 sol. mercuric 
chloride and then washed thoroughly in sterile water. The 
plants grew slowly, but on the whole satisfactorily. When 
they reached a height of 20 cm., one which had been infected 
directly from a tubercle was pulled and examined. The rest 
of the plants prospered and no more were pulled until they 
were in bloom. Close together on the roots of the plant first 
pulled there were 5 tubercles. On cutting they showed the 
rose red color, and the Y-forms were clearly visible on micro- 
=- scopic examination. Similar results had been obtained by 
previous investigators. More important, therefore, is the result 
of the infections with cultures known to be pure. Plants 
grown in pots infected with B. tuberigenus No. 3 from Rostock 
and others grown in pots infected with B. tuberigenus No. 5 
