

£gor | CURRENT LITERATURE 141 
base is attached to the posterior side of the excretory reservoir. The swell- 
ing mentioned lies against and below the concave side of the eye spot. This 
fact leads to a consideration of the effect of light on Euglena. As is the 
case in all motile cells, strong light repels and a moderate light attracts. A 
bright light will cause the active cells to round up and.encyst, if the stimula- 
tion be continued for several days. In darkness the cells round up, lose fla- 
gella, and divide. In spectrum rays, over seventy per cent. are drawn into 
the green-blue field. These blue rays are those absorbed by the red eye 
spot. As to the function of the eye spot, Wager makes two suggestions. First, 
that the absorbed blue rays stimulate the eye spot, which in turn stimulates 
the swelling on the flagellum ; second, that by cutting off certain rays, the eye 
spot produces a definitely unequal illumination of the enlargement, and as a 
result, an attempt at orientation. Both hypotheses, however, he puts forward 
tentatively, subject to further and more careful investigation.—PHILIP 
WRIGHTSON 
R. A. ROBERTSON (Trans. and Proc. Bot. Soc. Edinburgh 21: 290-298, 
Pés. 3. 1900) has recorded and illustrated some interesting observations on 
variations in Lycopodium clavatum. A luxuriant patch of this plant growing 
in a wood became exposed by a great storm which removed nearly every 
tree, and upon 20 to 30 per cent. of the erect axes the observed variations 
were found. Of this varying material 87 per cent. had extra branching of 
the strobilus-bearing axes, 66 per cent, showed branching of the strobili, and 
in 9 per cent. the strobili were completely metamorphosed into leafy shoots. 
The author suggests that these variations are of interest in reference to the 
phylogeny of the Lycopodiales, the branching of the strobilus and the steriliza- 
tion of sporogenous tissue being supposed to have played a part in the evolu- 
tion of the group.—J. M. C 
THE LITERATURE of lenticels has been further supplemented by James 
A. Terras (Trans. and Proc. Bot. Soc. Edinburgh 21: 341-352. Aés. 2. 1900), 
who has written upon the relation between the lenticels and adventitious roots 
of Solanum Dulcamara. We concludes that these roots do not arise below 
or grow out through lenticels, as is apparently the case in the majority of 
plants, but that their origin is entirely independent of the formation of lenti- 
cels. Furthermore, he states that the protuberances on the surface of the stem 
are not lenticels, but result from the formation of a mass of secondary tissue 
which originates in the reaction of the phellogen to the pressure set up by the 
elongating root below it. The lenticels only appear after the protuberances 
are fully formed.—J. M. C 
