644 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
quantity of the mineral ingredients, which are present in very small 
proportions in sea-water. A complete aeration is also necessary to the 
healthy growth of the plants. Although iodine is present in very large 
quantities in the ash of many seaweeds, we are at present entirely 
ignorant of the part which it plays in their vital economy. 
Adaptation of Fresh-water Algae to Salt-water.* — Herr A. Richter 
has undertaken a series of experiments with the view of determining to 
what extent freshwater algae can thrive in solutions of sodium chloride 
varying in concentration between 0 * 5 and 8 per cent. He finds that a 
number of species, belonging to a great variety of classes, Cyanophyceae, 
Diatomaceae, Chlorophyceae, and Characeae, can adapt themselves to 
these changed conditions, in some cases even continuing to assimilate, 
to divide, and to produce zoospores. The higher the organization of 
the alga, the less, as a general rule, is its power of adaptation ; Cliara , 
(Edogonium, Vaucheria , and Spirogyra have less capacity in this way 
than Oscillaria , Chlorella, Stichococcus, and Tetraspora. In all cases an 
increase in the size of the cells was observed, at first proportional to the 
degree of concentration. When the concentration was high, this was 
accompanied by malformation of the cells and by the conversion of the 
chlorophyll into a yellow or brown substance. The starch is at first 
consumed, but is again formed when the adaptation is more complete. 
Chylocladieae.t — Herr P. Hauptfleisch discusses the structure and 
life-history of the three genera Chylocladia , Champia , and Lomentaria , 
which make up the family Chylocladieae of the Rhodymeniacese. The 
following species are especially described — Chylocladia Jcaliformis , C. 
ovalis , Champia lumhricalis , C.parvula , Lomentaria articulata , L. clavellosa. 
All three genera are maintained, but the species are distributed among 
them in a different way from that proposed by previous authorities. 
The structure of the fructification is exceedingly similar in all three 
genera. The vegetative structure also differs but little. In neither 
of the three is a single apical cell to be detected. The distinctive 
characters given by the author are the following : — in Lomentaria the 
thallus is without diaphragms, the tetraspores are placed in depressions ; 
in the two other genera the thallus has diaphragms and the tetra- 
spores are scattered ; in Chylocladia the lobes of the cystocarps are 
unicellular; in Champia they are multicellular. The genus Gastro- 
chlonium must be sunk in Chylocladia . Chrysymenia and Bindera belong 
also to the Rhodymeniacem ; but are distinguished from the Chylocla- 
diese by the absence of medullary filaments. 
Cystocarps of Catenella Opuntia.J — Mr. R. J. Harvey Gibson has 
studied the structure of this seaweed, including that of the hitherto 
unknown cystocarp. Protoplasmic continuity exists between all the 
younger cells of the frond ; but later this seems to become interrupted 
by the growth of plug-like thickenings. Antherids and procarps are 
borne on the same plant, and usually near together. The mode of 
formation of the cystocarp differs in some points from the usual type 
in Florideae. Although the trichophoric systems are numerous, only 
* Flora, lxxv. (1892) pp. 4-56 (2 pis.). 
t Tom. cit., pp. 307-67 (2 pis.). 
j Journ. Linn. Soc. (Bot.) xxix. (1892) pp. 68-76 (2 pis.). 
