ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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trees were coming into bloom. In addition all diseased twigs or fruits 
should be cut out and burned, as they are the sources of new infection. 
This should be done at the time of pruning, and all twigs or mummied 
fruits — i.e. fruits shrivelled up by the fungus — should be collected from 
the ground and burned. A. L. S. 
The “ Browning ” and “ Stem-break ” Disease of Cultivated 
Flax (Linum usitatissimum) caused by Polyspora Lini g. et sp. n. 
— H. A. Lafferty ( Sci . Proc. Roy. Dublin Society , 1921, 16, 248-74, 
3 pis.). The great increase of flax cultivation in Ireland during the 
war led to the appearance of much disease of the fibres. The writer 
of the paper has devoted much attention to some of these diseases. 
Two symptoms, (1) “ browning ” (a turning brown of the plants before 
pulling time), and (2) “ stem-break ” (the fracture of the stems), have 
been traced to the action of the Hyphomycetous fungus Polyspora Lini. 
It is the seeds of the flax that carry on the disease, and the fungus has 
been found on seed of plants that had been produced in England and 
Scotland, as well as on seed purporting to come from Belgium, and also 
on seeds from other flax-producing countries. The various experiments 
of culture and of inoculation are described at length. The writer 
deprecates the use of seed from a diseased crop, but if no other is 
available the disease may be controlled to some extent by atomizing the 
seeds with a dilute solution of formaldehyde before sowing. A. L. S. 
Lichens. 
Research on Lichens of the Family Stictacese — Fernand 
Moreau (Ann. Sci. Nat. Dot., 1921, ser. 10, 3, 297-376, 3 pis., 20 figs.). 
The author has made a complete anatomical study of the different 
members of the family ; he has examined histologically seven different 
types, and is inclined to make the family one large genus with various 
subgenera. Moreau has also made a comparative study of the repro- 
duction ; he finds a trichogyne formed from the ascogonium which 
reaches the surface but degenerates without any evidence of copulation. 
Frequently the ascogonium itself degenerates. The various types of 
algge in thallus or cephalodia have also received attention ; he concludes 
that these live in symbiotic union with the lichen fungus, though he 
qualifies that statement by comparing the union to a gall structure or 
biomorphosis — only in the lichen it is the fungus that is incited to 
undue and abnormal growth. Further research he holds is necessary 
to determine the development of the thallus, or rather the development 
of the symbiotic relationship. A. Lorrain Smith. 
Lichens Living on Glass and their Mechanical Action on Church 
Windows. — Ethel Mellor (Comptes Rendus , 1921, 173, 1106-8). 
The writer has determined 22 vitricole lichens, including Ramalina sp. 
Xanthoria , Placodium , etc. She has found a new species, Caloplaca 
vitricola , with its new variety, var. violacea. The diagnoses are not 
given in the paper. She notes the corrosive action of the lichens on 
the glass, which may be affected to a depth of 1 • 6 mm. ; the greatest 
width of a corroded area was 5 mm. Mellor finds that glass has a 
