334 
Notes . 
material for the early stages of spore-formation, I pull up a plant on 
which one ear or more is smutted, and dissect out the ears of the 
eight or ten or more shoots that so far have no ears visible externally. 
Once I found a plant with two ears smutted and six or eight sound, 
but this was the only time that all the ears on a plant were not equally 
affected; and once I found an ear with the three lowest 'kernels alone 
smutted while all those above were normal. To keep up my stock of 
spores for germination in class-work, I gather the smutted ears before 
the spores are shed, and keep them in small tin tobacco-boxes. On 
one occasion a small beetle got shut up too, and was imprisoned for 
a week or two before I found and released it. I noticed many spores 
adhering in short threads, really the excreta of the said insect. I tried 
the germination of the excretal and normal spores in a culture-cell 
(made by fastening a glass ring to a slide and growing the spores in 
a hanging drop of water on the cover-slip inverted on the ring), and 
found the former to germinate in about half the time required for the 
latter. For this summer’s material I smutted some Barley with spores 
taken from Barley (Row 5 of my plot at the Botanic Garden), some 
with spores from Oats (Row 7), and some with spores from Wheat 
(which, however, gave no result). Omitting details, I may say that 
I found 70-80 % only of the grain grew, and I gathered eighty 
smutted ears from Row 5 and forty-six from Row 7, amounting to 
37 % and 21 % respectively of the total number of ears produced. 
Phytophthora infestans. — As Potatoes are not to be absolutely 
depended upon, and as growing and infecting successive sets of 
potato-tops under bell-jars involves much space and time, I have for 
the past three years used Solanum laciniatum as class-material. I can 
rely on finding Phytophthora infestans upon it and in good condition, 
and its petioles and midribs furnish material much superior to potato- 
leaves. I prefer to gather all my Phytophthora material before the 
dew is off, and I keep it in a vasculum until my class at n.o, when. 
I use it fresh. 
W. G. P. ELLIS. 
Botanical Laboratory, Cambridge. 
THE FUNCTIONS OF LATEX.— Although several attempts 
have been made to ascertain the functions of latex in plants, 
they have not led to any very conclusive information respecting it. 
Accordingly, at the suggestion of Prof. Marshall Ward, I undertook an 
