ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 691 



Structure of Caliciese.* — E. Neubner has investigated the structure 

 and development of this little-known family of lichens, especially the 

 species Cyphelium tricJiiale, Calicium populneum, O. roscidum, Acolium 

 tympanellum, and A. tigillare. The thallus varies from true crustaceous 

 to granular-pulverulent, and offers an additional illustration of the 

 fallacy of the old classification of lichens into those with homoomerous 

 and those with heteromerous thallus. 



The gonidia of the Caliciae are of three kinds : — Cylindrical, cor- 

 responding to Stichococcus hacillaris among unicellular algse ; and 

 spherical, corresponding to the forms Cystococcus and Pleurococcus. 

 The course of growth of the thallus is that described by Schwendener 

 under the term " orthogonal-trajectoral," and which belongs especially 

 to the fruticose and foliose forms. For the greater number of species 

 the gonidia closely resemble Cystococcus humicola Nag. The Pleuro- 

 coccus form of gonidium does not correspond precisely to any known 

 species of that genus, but the author regards it as a modification of 

 P. vulgaris. These globular gonidia have a strong tendency to assume 

 a cylindrical form, accompanied by a decrease in size, thus becoming 

 transformed, owing to the mechanical circumstances of their environ- 

 ment, into the typical Stichococcus hacillaris. The genera Stichococcus 

 and Pleurococcus cannot therefore be maintained as distinct. When 

 freed from the enveloping hyphse the Stichococcus may either remain 

 permanently in that condition, or may become again transformed into 

 its original Pleurococcus form. Transitional forms of all kinds may 

 be observed, and the author compares these two stages of the same 

 organism to the bacterium and coccus stage of bacteria. 



Algse. 



Structure and Fertilization of Floridese.t — F. Schmitz has 

 made a detailed examination of the most important points in the 

 structure of the vegetative and reproductive organs of several families 

 of Floride^, of which the following are some of the more important 

 details. 



The thallus of the Floridese is always composed of branched fila- 

 ments, which are sometimes held together by a more or less dense 

 gelatinous envelope, sometimes by a very dense and tough intercellular 

 substance, so closely that they form a pseudo-parenchyma; or they 

 may be quite free. The separate filaments increase in length by. 

 apical growth, which is often followed by a very strong intercalary 

 growth of the separate cells. Whenever a cell divides, a peculiar 

 opening is formed in the septum, by means of which the two new cells 

 remain in communication with one another so long as they are in a 

 living condition; they are usually circular, and are closed by ex- 

 tremely thin membranes, through which pass strings of protoplasm 

 connecting the two cells. There is not usually any passage of the 

 cell-contents from one cell to another, which does, however, occur 

 through larger orifices in some Corallinaceje. 



* Flora, Ixvi. (1883) pp. 291-301, 307-17 (3 pis.), 

 t SB. Akad. Wiss. Berlin, 1883, pp. 215-58 (1 pi.). 



