336 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
strong affinity for humidity, and is affected by the carbonic acid of the 
atmosphere, an effect that is accelerated by the lichen growth. The 
lichen is closely applied, and, as it burrows, it lifts minute flakes of 
glass which can be seen incorporated in the tissue. A yearly cleansing 
of the windows should be sufficient to remove all lichen growth. 
A. L. S. 
Corticolous Graphidacese.— G. Bioret (Ann. Sci. Nat. Bot., 1922, 
ser. 10, 4, 1-65, 11 pis.). A careful and detailed account of the genera 
of Graphidaceas that grow on bark, usually under the bark (hypo- 
phloeodal). There is considerable difference in development of the 
vegetative thallus among these genera, that of Graphis reaching the 
highest stage, while Aorthonia is the least advanced. The nature of the 
substratum — rough or smooth bark, etc. — exercises undoubted influence 
on the development. The author agrees with Lindau that the hyphae 
of the lichen do not dissolve the walls of the host cells ; they penetrate 
by means of accidental openings. In his summing up he notes the 
action of heredity, more marked in the reproductive organs, and of 
adaptation to surroundings which mainly affects the thallus. The 
plates are most of them coloured, and add greatly to the interest of 
the paper. A. L. S. 
Physiological Researches on Lichens. — Eva Mameli (Atti 1st. 
Bot. Univ. Pavia , 1920, 17, 147-57). The author is dealing with 
carbohydrates, and has tested a large series of lichens for these bodies 
by means of various reagents which she describes. In addition to 
lichenin and isolichenin she has determined the presence of three other 
carbohydrates. 1. Glycogen : this substance she has found more or 
less abundant in the gelatinous substance of homoiomerous lichens — 
that is, of those associated with Cyanophyceae, Gollema , Leptogium , 
Sgnalissa, etc. 2. Starch she found in many heteromerous lichens, 
either in the gonidia or in close relation with them. 3. Amyloid : an 
insoluble amyloid was found to be present in the hymenium of a large 
series of lichens ; it gives the blue reaction with iodine so characteristic 
of lichen asci. Finally, the author states that the quantity of glycogen 
and starch present in the thallus is in direct relation to the photo- 
synthetic process. A. L. S. 
Critical Note on some Modern Theories as to the Nature of 
Consortism in the Lichen Thallus. — Eva Mameli ( Atti 1st. Bot. 
Univ. Pavia , 1920, 17, 209-26, 1 col. pi.). There is first a review of 
the various theories propounded by lichenologists as to the parasitic or 
symbiotic relation of the fungus to the alga. The author then proceeds 
to give the results of her own researches o;i the lichen thallus. She 
finds dead algae occurring sporadically in the thallus, but their presence 
does not in her opinion affect the question as to the nature of the 
association with the fungus ; they are to be found chiefly in the deeper 
layers of the thallus, and may have succumbed to the want of light, 
and also in colonies of algse the number of dead cells is equally abun- 
dant. The writer found very rarely any haustoria from the fungus 
piercing the algal cells, so rarely that the question of parasitism is ruled 
