SCIENTIFIC PROCEEDINGS. 
Abstracts of the Communications. 
Forty-first meeting. 
The Rockefeller Institute for Medical Research. December 21 , iqio. 
16 (54i) 
Retention of normal polarity in centrifuged stems of Tubularia. 
By MAX W. MORSE. 
[From the Harpswell Laboratory and the Biological Laboratories of 
Trinity College, Hartford, Connecticut.] 
Stems of the hydroid, Tubularia crocea, were cut from the 
colony, which had been taken directly from the sea. The hy- 
dranths were removed by cutting them from the stems immediately 
below their attachment. A small branch from the stem was left 
intact to serve for orientation, and the hydranth which belonged 
to this branch was cut off. 
These stems were placed in specially prepared tubes fitted 
to a hematocrit centrifuge, operated by hand. Rotation was made 
at varying speeds and for varying intervals of time ranging from 
a minimum speed of rotation of about two hundred and forty per 
minute to a maximum of about six hundred rotations per minute. 
A greater speed than this resulted in forcing the contents of the 
perisarc tube out at the distal end. The periods of time of rota- 
tion varied from a minimum at highest speed of one minute to a 
period of maximum operation at medium number of rotations 
per minute (approximately three hundred, the centrifuge being 
about one-in-four, but there was no speedometer available to 
accurately measure the number of rotations at the higher speeds), 
for one half hour. 
The behavior of Tubularia stems under all of these conditions 
was uniform and unvarying. When regeneration occurred, which 
was true in 100 per cent, of the cases under observation, as the 
stems lay horizontally in finger-bowls, the hydranth appeared at 
29 
