



Q2 
distinct species. The simplest way seems to call them biological 
species and have done with the controversy. 
The facts involved are, however, of great practical impor- 
tance—for instance, adjacent crops of wheat and rye, or of 
wheat and oats or barley may be grown without fear of in- 
fecting one another :nor need the proximity of 7 riticum repens 
or Poa in the hedge banks be dreaded as sources of infection. 
During the present year I have performed some experiments 
with Puccinia graminis which may be worth recording in so far 
as they corroborate Eriksson’s statements and show that the 
results obtained by him hold good in this country. 
Early in the year my friend Mr. F. Barrington kindly ob- 
tained for me a supply of over-wintered Puccinia graminis on 
Poa trivialis from Narborough near King’s Lynn. ‘The spores 
were found to germinate freely, and on the 6th May Mr. K. B. 
Williamson and myself applied them to a small barberry bush 
in my garden; in due course the pycnidia appeared, and on the 
oth of June perfect acidiospores were developed, on this day 
these zcidiospores were applied to a series of plants growing in 
pots, viz: Poa trivialzs, Triticum repens, barley, rye and oats. 
On the oth of July the uredo appeared on the Poa but not on 
any of the other plants. In order that they might have a fait 
chance of being infected they were planted in a circle round the 
barberry, which was just a small bush not more than a foot in 
height. They were thus not only exposed equally to the 2cl- 
diospores but also to the uredo spores, which had already formed 
on the Poa. From time to time these plants were examined 
until they were finally pulled up on the 15th of September ; at 
which time careful examination showed them to be fungus-free 
with the exception of the Poa, on which teleutospore beds were 
present. Thus Eriksson's statement is absolutely confirmed 
as to the species on Poa, being biologically distinct from those 
on oat, barley, Triticum repens and rye. 
AKcidiospores on Berberis Plant Infected. Date. Date of first 
vulgaris from result. 
1304. Poa trivialis Poa trivialis 18 June- go July 
1305. 3s Triticum repens 18 June —- 
1300. ‘ * Hordeum vulgare 18 June — 
L207. re Avena sativa 18 June — 
1308. ie Secale cereale 18 June — 
Further cultures were also made on 18th June by applying 
the uredospores on Triticum repens to another series of pot 
plants viz: Tr. repens, barley, wheat, rye, oat and Poa trivialts. 
On the 3rd August the Z7zdecum repens had well developed 
uredospore beds but the other plants remained free. On the 
15th September these plants were gathered and carefully ex- 








