220 BOTANICAL GAZETTE [MARCH 
Photic sense organs.—GuTTENBERG' has demonstrated that two of the om- 
brophilous species of his local flora have a photo-sensitive epithelium, whose 
response consists in maintaining the leaf in the transverse heliotropic position. 
The mechanism is essentially the same as was found by HABERLANDT in the so- 
called velvet leaves, so abundant among the ombrophilous species of the tropical 
hydrophytic forests. The épidermal cells function as converging lenses, so that 
the protoplasmic membrane which covers the floor of the cell is not uniformly 
illuminated. In HABERLAND?I’s studies the bright spot was centrally located, 
but GUTTENBERG finds that for his species that it is excentric, because the 
papillosity is not centrally located. The result is the same in both cases, for 
the leaf is attuned to the distribution of interior illumination which exists when 
the leaf is in the transverse position. Actual tests showed that the petiole is 
not a factor in securing this position. Curiously enough the leaf assumes the 
horizontal position in diffuse light, such as occurs under the open sky on a 
cloudy day. In this cee, however, the internal distribution of light is the reverse 
of that which exists under parallel rays, the central area of the floor wall being dark 
with a margin of increasing brightness. The stimulus apparently consists in an 
unequal illumination of the cell lumen.—RAyMonpD H. Ponp. 
Nature of chromatophores.— MErEsCHKOWSKY'S holds that these bodies are 
not organs of the plant cell and never have been, but are foreign organisms 
which penetrated into the colorless plasma of the cells and live there as 
symbionts. In support of this notion he adduces the facts that the chromato- 
phores multiply continuously by division and do not arise de novo; that they are 
in high degree independent of the nucleus; that they are completely analogous 
with zoochlorellae and zooxanthellae which inhabit hydras, infusoria, etc.; that 
there are organisms, (e. g., the lower Cyanophyceae, such as Aphanocapsis and 
Microcystis) which can be considered as free-living chromatophores; that 
certain Cyanophyceae actually live as symbionts in the cell plasma. This theory 
he thinks, is the only possible explanation of the polyphyletic origin of primeval 
plants, which were merely amoebae and flagellates into which Cyanophyceae 
migrated; that the green, red, and brown Cyanophyceae account for the algae of 
these colors; that the plant cell-wall is due to the formation, by the symbiotic 
chloroplasts, of carbohydrates easily polymerized into cellulose ; which w. 
makes impossible the further taking of solid food and entails the quiescent nature 
and simple organization of plants, minus nerve, muscle, and psychic life. Here 
is another pyramid of theory resting on its apex.—C. R. B 
‘4GUTTENBERG, H. R., von, Die Lichtsinnesorgane der Laubblatter von Adoxa 
Moschatellina und Cynocrambe prostrata. Ber. Deutsch. Bot. Gesells. 23:265-273- 
pls. 10, II. 1905. 
5 MERESCHKOWSKy, C., Ueber Natur und Ursprung der Chromatophoren im 
OT en a Biol. Centralbl. 25: 593-604. 1905. 
