153 
EXPLANATION OF PLATES. 
OLIVE TUBERCULOSIS. 
Plate XIV. Olive branch 1H inches long, bearing 29 tubercles, only part of which are 
seen in the plate, and none are fully matured. Several of the tuber¬ 
cles have but recently broken through the bark of the branch. This 
branch was cut July 29, 1890, from a badly infected olive tree growing 
iu an old grove two miles south of Palma, in the province of Naples, 
Italy. Photograph of fresh material. 
Plate XV. Fig. 1. Well-matured olive tubercles of natural size, showing the usual 
ruptured condition of the top. The rupturing is preceded by 
a slight pitting at the surface, as shown iu the lower tumor. 
Material from near Genoa, Italy. 
2. Olive tumors from the same source as those of Fig. 1. The lower 
tumor shows au opening through which some insect has es¬ 
caped, which inhabits the old tumor, and which may assist in 
spreading the disease. 
3. Section through a tumor. Shows the hypertrophy of the tissue 
and the degeneration at the central part of the tumor where 
the bacilli are situated. After Briosi and Cavara. 
4. Bacillus oleoc (Arcangeli), Trevisan. From figures of stained 
slide preparations by Briosi and Cavara. I have seen the 
original preparations given in Figs. 3 and 4. 
RECENT INVESTIGATIONS OF SMUT FUNGI AND SMUT DISEASES. 
AN ADDRESS DELIVERED BEFORE THE SOCIETY OF AGRICULTURISTS OF BERLIN, 
FEBRUARY 17, 1888. 
By Dr. Oskar Brefeld. 
Full Professor of Botany in Mil ns ter in TV. 
Translated from Nachrichten aus deni Klub der Landwirthe zu Berlin , Nos. 220-222, by 
Erwin F. Smith. 
(Continued from p. 71.) 
For the solution of the first question some important data have been 
pointed out already in speaking of the mode of infection, to wit, the 
application of the germs and their penetration into the host. From the 
results of the first five series of experiments it is evident that the period 
of receptivity in the seedlings is very transitory. The slower this stage 
of growth the more probable it is that the germ which has penetrated at 
the right spot will actually reach the growing point in the given time ; 
and this must be reached if the nascent Jdossoms and fruits (the subse¬ 
quent location of the smut beds) are to become smutty. On the con¬ 
trary, the more rapid this stage of growth the less must be the prob¬ 
ability that the germ can reach the growing poiut in the short time be¬ 
fore the seedling begins to elongate. And from this poiut of view the 
most extreme case would be when a very greatly hastened development 
of all seedlings altogether prevented the passage of the penetrated 
germ into the growing point; iu this case, in spite of all penetrated 
germs, the appearance of the smut diseases would be impossible. 
, 23023—No. 4-2 
