688 SUMMARY OF CUERENT RESEARCHES RELATING TO 



microgonidia, arranged in a moniliform manner and filling up tlie 

 hyplise. The protoplasmic nature of these bodies can be readily 

 proved ; but no cell- wall can be detected nor any green pigment. 

 They may lie for weeks in absolute alcohol or ether without the green 

 colour being removed ; this colour depending on a peculiar property 

 of absorption and refraction of these very dense protoplasmic bodies. 



In Verrucaria rupestris var. rosea and Hymenelia ccerulea the 

 thallus is composed for the most part of branched colourless thin- 

 walled hyphae, containing a larger or smaller number of bladder-like 

 bodies of roundish, ovoid, pear-shaped, or ellipsoidal form. In the 

 upper zone of the thallus which bears the gonidia, these bladders 

 not unfrequently contain two or four daughter-cells, which are not 

 gonidia although possessing a green tint. With iodine and sulphuric 

 acid the cell-walls of these bladders and of their daughter-cells 

 become yellow, while those of the gonidia turn a beautiful blue. 



In Petractis exanthematica the alga which forms the gonidia is a 

 Scytonema, and the lichen possesses the peculiarity of that genus that 

 the hyphse are of very different thicknesses. In Verrucaria fusca we 

 find also a Scytonema in the form of gonidia, and in addition masses 

 of blue-green cells resembling a Gloeocapsa, and apparently resulting 

 from the breaking up of the Scytonema-Alavaents. The same genetic 

 connection between Scytonema and Gloeocapsa occurs, therefore, within 

 the lichen-thallus as in the free algae. 



The author describes a new genus of lichens, Eolichen, with the 

 following characters : — Thallus roundish, gelatinous, pellicular, 

 1-5 mm. in diameter, adhering to the substratum by the entire 

 surface. The gonidia are species of Sirosiphon and Scytonema ; the 

 hyphte are segmented in a leptothrix-fashion. Apothecia globular, 

 brownish-red, pellicular, perforated at the apex. Spores in eights, in 

 two indistinct rows, inclosed in a narrow club-shaped ascus. Para- 

 physes wanting. Three species are described : — E. Heppii, compactus, 

 and clavatus. In the last species the nutrient alga is a Scytonema, in 

 the two others a Sirosiphon. 



Algo-Lichen Hypothesis.* — Eev. J. M. Crombie says that " in 

 addition to the various direct and indirect arguments which have 

 been adduced against this theory, another, and in some respects, a 

 still more convincing proof, has quite recently been brought under 

 notice by Dr. Nylander.j In his observations upon Gyalecta lampro- 

 spora Nyl., a new species from North America, collected by Mr. 

 Willey, of which a full diagnosis is given, he writes : ' Each goni- 

 dium of this Gyalecta is distinctly seen to emit from its thickish 

 cellular wall (as do also the young gonidia) a firm medullary filament 

 and often two such filaments, characteristic of the nature of lichens. 

 It is most manifest that these licheno-hyphae are productions, and 

 indeed continuations, of the cellular wall of the gonidium itself.' In 

 the species under notice it may be mentioned that the thallus is not 

 corticated, and that the gonidia are most frequently chroolepoidly 



* Jom-n. of Bot., xxiii. (1885) p. 219, 

 t ^^om, Ixviii. (1885) p. 313. 



