SepTeMBER 20, 1918] 
in an apparently peaceful condition, seems 
worthy of note. 
The colony in which the dual queens were 
found is colony 95 of the Massachusetts Agri- 
eultural College Bee Yard, and the data in re- 
gard to its history were given me by Dr. Gates, 
with whose permission these notes are pub- 
lished. 
On May 23, 1918, Dr. Gates had inspected 
this hive and found only the old queen. No 
queen cells were present and the colony was of 
medium strength, occupying only one story of 
the hive. The queen was introduced to this 
colony on August 1, 1917, and was therefore 
not old, and came of strong stock which had 
been selected for four years to resist the Euro- 
pean foulbrood. 
Thirteen days later, on June 5, 1918, on 
opening the hive a large number of queen cells 
was first noted; there were seven in all, three 
cells containing eggs, one a larva about four 
days old, two with young pupe, and one empty 
cell with its cap thrown back, showing that a 
queen had recently emerged. The varied ages 
of the developing queens in these cells was in- 
terpreted by Dr. Gates as indicative of a 
tendency towards “supersedure,” that is, the 
replacement of the old queen by a new one. 
After a short search, a young virgin queen 
was found on the comb, her appearance show- 
ing that she had only emerged a few hours be- 
fore. On another comb the old queen was 
found laying. Her wings were slightly 
frayed, although she was less than a year old, 
and her abdomen was considerably larger than 
that of the virgin queen. 
In normal eases of “ supersedure” the par- 
ent queen is destroyed by the workers prior to 
the emergence of the virgin, and in swarm- 
ing it is known that the parent queen leaves 
the hive on the day that the cell of the new 
queen is capped. 
Such a case of “supersedure,” with the sur- 
vival of both parent and daughter queens in 
the same colony, suggests a return of the prob- 
able ancestral condition of multiple queens, 
the condition that prevails to-day among 
bumble bees in the late summer, among certain 
wasps, and in ants. 
SCIENCE 
295 
After the discovery of the dual queens in a 
single colony, the old queen with most of the 
brood was confined in the second story of the 
hive, with a “queen excluder” above the first 
story, in which the virgin queen was placed 
with one sheet of brood and nine empty combs. 
The subsequent history of the old or parent 
queen may explain why her workers attempted 
to supersede her. 
CaroLinE B. THompson 
WELLESLEY COLLEGE 
PARAMECIA WITH EXTRA CONTRACTILE 
VACUOLES 
THREE years ago I found a race of Para- 
mecium caudatum which possessed more than 
two contractile vacuoles. A preliminary note 
on the behavior of these vacuoles was pub- 
lished in this journal (1915, Vol. 42) and two 
years later an account of the morphology, 
physiology and genetics of this new race ap- 
peared in the Journal of Experimental Zoology 
(1917, Vol. 23). In this paper the following 
conclusions were presented: 
1. The number of contractile vacuoles range 
from two to seven. Three- and four-vacuoled 
forms are most abundant. 
2. Apparently any individual has the poten- 
tiality for higher numbers of vacuoles. The ap- 
pearance of the vacuoles depends on two things 
—(a) the rapidity of division; rapid fission 
does not give time for the vacuoles to form, 
(b) the amount of catabolic waste in the en- 
vironment. If the percentage of waste is rela- 
tively high the average number of contractile 
vacuoles in the paramecia of the culture is 
high. In new cultures made up with fresh 
hay infusion the average number of vacuoles 
is low. The effect of rapidity of division can 
be partially overcome, since old cultures in 
which the rate of fission has been increased 
through the addition of new food show an 
average vacuole number much higher than 
found in fresh infusions. 
3. Although several generations may pass 
without the appearance of extra vacuoles the 
potentiality for these organs is inherited and 
merely waits for the proper (apparently en- 
vironmental) conditions to call them forth. 
4. The extra vacuoles are, in almost all 
