UNIVERSITY OF CALIFORNIA PUBLICATIONS 
IN 
ZOOLOGY 
Vol. 9, No. 5, pp. 249-251 May 28, 1912 
OXYGEN AND POLARITY IN TUBULARIA 
BY 
HARRY BEAL TORREY 
It is a familiar fact to students of regeneration that in the 
regeneration of a segment cut from a stem of Tubularia, two 
hydranths are produced, one at each end of the piece (which 
is then termed heteromorphic), and that the distal hydranth 
appears earlier than the proximal. It is also well known that the 
development of the proximal hydranth can be accelerated by 
ligating the stem at almost any level. 
According to Loeb (1904) this acceleration is connected 
causally with the diversion by the ligature of the currents cir- 
culating in the stem. I have attempted to show (1910), however, 
that it is due to quite another effect of the ligature, namely, the 
suppression of the regeneration of hydranths at the hgature on 
either side owing to an inadequate supply of oxygen at these 
points. The same proximal acceleration, associated with the same 
suppression of distal development, may be produced, as Loeb 
(1906) long ago pointed out, by burying the distal ends of the 
stem segments in sand. The proximal ends thereupon produce 
hydranths more rapidly than would have been the case had 
oxygen had free access to the distal ends. Loeb’s surmise that 
‘ack of oxygen is responsible for the fact that no polyp can be 
formed except at a free end of a stem, since the chitinous surface 
of the stem is very little permeable for oxygen,’’ is clearly 
supported (see Torrey, 1910) by the following facts: (1) in 
Corymorpha, the stem is naked, and hydranths do develop at the 
ligature, that is, immediately below it; (2) in Tubularia, develop- 
ment can be suppressed at either end of the stem by slipping over 
