624 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the refractive tufts. The details of this special mode of reproduction 

 are described. 



In considering the glistening property of the cells, the author reviews 

 the incipient " eyes " of forms like Peridinea, and emphasizes the probability 

 of the " eye " bsing primitively trophic rather than sensory. Besides the 

 sensory function, the primitive " eye " is adapted to the absorption of solar 

 energy. Nor is this primitive function wholly lost in higher grades of 

 evolution. 



Formation of Pores in Sphagnacese.* — According to Herr K. G. 

 Limpricht, the presence of pores in the cortex of the stem of Sphagnacese 

 is a more general phenomenon than is usually supposed, occurring 

 universally, except in the cuspidatum-group. Besides the sharply defined 

 pores, there are also frequently in the leaves larger irregular orifices in the 

 cell-wells caused by resorption. Both kinds of orifice are connected with 

 the more or less abundant formation of fibres. 



Algae. 



Structure and Development of the Thallus in Floridese. t — M. M. 



F. Debray describes the structure and development of the thallus in the 

 genera Chylodadia, Ghampia, and Lomentaria. At the growing point are a 

 number of apical cells having their apices in close contact, which divide 

 repeatedly by transverse septa independently of one another, producing rows 

 of cells. The divisions in the different rows correspond to one another so 

 closely as to produce a uniform tissue. Each cell of these hyphae divides 

 immediately beneath the growing point by a longitudinal wall, the cortical 

 cells being in this way separated. The cortical cells divide again by walls 

 placed vertically to the surface but irregularly, a connected layer being thus 

 formed which surrounds the whole of the branch. 



The branching of the thallus is either dichotomous or lateral ; and 

 adventitious shoots may arise on older parts of the thallus when the cortex 

 consists of only a single layer ; or they are formed without any definite 

 position from inner cortical cells. 



Parasitic Alga of Emys europsea.J — Dr. A. Peter discovered in the 

 horny tissue of the carapace of Emys europsea a chlorophyllaceous alga, 

 DermatopTiyton radians, which forms fronds with a diameter of even 13 mm. 

 The alga penetrates the horn and by its growth eventually forms a cup- 

 shaped projection. It is a real parasite, as it derives its nourishment from 

 its host. 



Padina.§ — Dr. F. Hauck proposes to classify the various forms belong- 

 ing to this genus, hitherto considered as constituting one species only, under 

 three groups, viz. : — 



(1) Reproductive organs developed on both sides of every second filament- 

 zone, forming, when ripe, double zones, separated from one another by a 

 more or less conspicuous filament-zone. (Type : P. pavonia.^ 



(2) Eej)roductive organs developed on the upper side of every second 

 filament- zone, forming, when ripe, intermediate bands between each second 

 interstice formed by the filament-zones. (Type : P. Commersoni.) 



* JB. Schles. Gesell. vaterl. Cultur, Ixiii. (1886) p. 199. Cf. this Journal, 1886, 

 p. 656. 



t Bull. Scieut. Depart, du Nord, ix., 14 pp. and 4 figs. See Bot. Centralbl., xxix. 

 (1887) p. 354. 



X SB. Geyell. f. Morphol. u Physiol. Munch., ii. (1887) pp. 117-8. 



§ Hedwigia, xxvi. (1887) pp. 41-5. 



