ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 101 



(S. saccata and Loharia) the alga penetrates into the mediillary layer ; 

 or sometimes (*S^. crocea and hispora) it penetrates still higher into the 

 thallus, and spreads into the yellowish-green gonidial layer, which is 

 often replaced by it ; or finally {Loharia amplissima, Lecanora gelida, 

 and Lecidea panceola) the gonidial and cortical layers are broken 

 through, and the cephalodium emerges on the upper side of the 

 thallus. 



Under the name Pseudocephalodia (as distinguished from cepha- 

 lodia vera) the author describes such as are formed in the protothallus 

 by the germinating hyphae investing algal colonies of some other type 

 than the normal gonidia of the lichen. They are but slightly united 

 with the other parts of the thallus, and exhibit a tendency towards 

 independent development. At present they have been observed in 

 only a few lichens : — Solorina saccata var. spongiosa, Lecidea pallida, 

 and probably in Lecanora Jiypnorum and Lecidea panceola. Inter- 

 mediate forms also occur between the various kinds of cephalodia. 



In some of the above-named species the author states that the 

 pseudocephalodia develope in the same way as is described by 

 Schwendener from the thallus of lichens, a point of considerable im- 

 portance with regard to the Schwendenerian theory of the origin of 

 lichens. In the true cephalodia we have in fact a double parasitism, 

 or mutual symbiosis of algaa and fungal hyphae. 



Lichens from the Philippines.* — B. Stein describes a number of 

 lichens forwarded by Dr. Schadenberg from Mindanao in the Philip- 

 pines. Among them is a new genus, Dumoulinia, belonging to the 

 Lecanore^e, of which he gives the following diagnosis : — " Thallus 

 crustaceus uniformis ; apothecia lecanorina, superficialia, excipulo 

 crasso cupulari ; sporfe quaternse, maximee, hyalinae, tetrablastae." 



Algae. 



Protoplasmic Continuity in the Floridese.f — T. Hick has made 

 an extensive series of observations on a large number of species 

 belonging to the more important genera of Floridete, with special 

 reference to the question of protoplasmic continuity. He finds in all 

 the species examined that there is such a continuity, and that of the 

 clearest and most definite character. In the simpler filamentous 

 types, such as Petrocelis cruenta and Callithamnion BotJiii, the pro- 

 toplasm of each cell is united with the protoplasm of contiguous cells 

 by means of a fine protoplasmic thread. This occurs throughout the 

 whole plant. In the more complex types, such as Callithamnion 

 roseum, arhuscula, and tetragonum, the arrangements for continuity are 

 of a more elaborate character. The contents of the axial cells are not 

 only united with one another, but also with those of the cortical cells, 

 however numerous these may be. The cortical cells also display 

 continuity inter se. Ptilota elegans is a most instructive form, as 

 here the connective threads may be easily traced from the tips of the 

 ultimate branchlets to the base of the stipes of the frond. As the 



* JB. Schles. Gesell. Vaterl. Cult, 1883, pp. 227-34. 



t Pi'oc. Brit, Assoc. Adv. Sci,, 1883. Cf. Nature, xxix. (1883) p. 581. 



