930 SUMMARY or CURRENT RESEARCHES RELATING TO 



beneath the terminal violet sporangium; it occurs on horse-dung. 

 The amceb* appear among the spores in the same way as in Dictyo- 

 stelium, and are provided with vacuoles and a nucleus. These amoeba 

 do not,' however, coalesce into a true plasmodium before the formation 

 of the sporangium ; they can be separated from one another by the 

 slightest pressure, and constitute what may be termed a pseudo- 

 plasmodium, from which the sporangium is directly formed. Almost 

 before the amcebge have entirely lost their pseudopodia the formation 

 of the sporangium begins ; a central portion of the mass of amoebae 

 becomes differentiated, and developes into the pedicel, each amceba 

 becoming a pedicel-cell. As soon as the formation of the pedicel is 

 completed, the remaining mass creeps to its apex and collects into a 

 ball; each amceba becomes a spore, and the whole a pseudo- 

 sporangium, which is at no time enveloped in a membrane. 



liichenes. 



Relation of Lichens to the Atmosphere.*— G. Bonnier and L. 

 Mangin have determined that under circumstances most favourable to 

 their development, viz. in darkness, diffused light, sunshine, and at 

 different temperatures from 10° to 32°, several lichens — Cladoma 

 rangiferina, Evernia Prunastri, Parmelia caperata, and Peltigera- 

 cawma— display, as the net result of the influence on them of the 

 air, an absorption of oxygen and disengagement of carbon dioxide. It 

 follows that, under the most favourable conditions, the action of chloro- 

 phyll does not compensate respiration ; and that, as a consequence, 

 lichens cannot obtain from the atmosphere all the carbon which they 

 require for building up their tissues. 



Alg'se. 



Algae of the Red Sea.f — A. Piccone publishes a list of 235 algae 

 found in the Eed Sea, mostly in the Bay of Assab, with descriptions 

 of a number of new species and varieties. Four genera and not less 

 than 99 species are peculiar to the Eed Sea algal flora; and the 

 general af&nities are much closer with the forms of the Indian Ocean 

 than with those of the Mediterranean. The great feature of the 

 algology of the Eed Sea is the enormous number of species and 

 varieties of Sargassum, nearly all of them endemic; it is also 

 characterized by the scarcity of diatoms, and of green algae generally ; 

 the Laminarieae are also altogether wanting. 



Afghanistan Alg8e.| — Dr. J. Schaarschmidt gives an annotated 

 list of 60 species of algae collected in Afghanistan in 1880. They 

 were found chiefly adhering to specimens of Ammannia jpentandra 

 Eoxb., and forming fine bluish-green incrustations around the stems 

 and on the leaves. Many interesting forms were found (perhaps 



* Bull. Soc. Bot. France, xxxi. (1884) pp. 118-9. 



t Nuov. Giorn. Bot. Ital., xvi. (1884) pp. 281-332 (3 pis.). 



j Journ. Linn. Soc. Lend. (Bot.) xxi, (1884) pp. 241-50 (1 pi.). 



