1897.] General Biology. 975 
fluid, however, for they are repelled by the latter also, but they keep 
in a zone of weak concentration o » The chemotactic movements 
of Paramecium were seen also in their repulsion by strong solutions of 
all acids, including CO,, by all alkaline solutions, to which category 
the culture fiuid belonged, and to certain neutral salts and organie 
compounds. Towards other organic substances, e. g., sugar, glycerine, 
urea, Paramecia is indifferent. Tonotaxis plays no important part in 
the normal activities of the organism. The reason why the infusoria 
are not forced beyond the circumference by the electric current is that 
they are less strongly electrotactic than chemotactic. 
The following weighty conclusion is now drawn: Since infusoria are 
negatively tactic to their native fluid and positively tactic to the unad- 
vantageous CO,, negative or positive taxis is not necessarily an adap- 
tive movement, is not always determined by its advantage to the spe- 
cies. 
PALZONTOLOGY. 
Archegosaurus.'—The results of this preliminary paper are based 
on the rich material of Archegosaurus contained in the “ Kgl. Museum 
fir Naturkunde” and the collection of the “ Kgl. geologische Landes- 
anstalt in Berlin, The archegosaurs are preserved in clay-geodes, 
and in spliting these the bones are generally broken. After the 
bones had been removed with chisels or fine steel-needles, a mixture of 
gelatine and glycerine was poured over the plates and very good reliefs 
of the skeleton were thus produced. 
Jickel intends to write a monograph on Archegosaurus and gives 
only the more important results. He commences with the skull, and 
afterwards discusses the vertebral column, the limbs and the dermal 
skeleton. 
The skull.—In the palatal region he finds some differences from the 
statements so far given. There exist series of teeth on the inner sides 
of the vomers and palatines, which show essentially the same arrange- 
ment as in the Labyrinthodontia. Larger teeth are placed between the 
anterior ends of the choanæ, and behind these. The choanæ are very 
much longer than in the Labyrinthodonts, This elongation is certainly 
in relation to the anterior extension of the muzzle of Archegosaurus. 
1 Jackel, Otto. Die Organisation von Archegosaurus. Zeitschr. deutsche Geol. 
Ges. Jahrg., 1896, Heft 3, p. 505-621, fig. 10. 
66 
