26 
It was found that Spiruxfomum sp. was an ideal species 
for these investigations, as it was not injuriously affected by the 
solutions, and was very active and sensitive to the test solu- 
tions. Species A and B were also uninjured by the solutions, 
but did not, as a rule, re-act quite so quickly as Spi/Tjsfomum 
sp. Opalina was very liable to injury by decinormal solutions 
— the action of KCl and of NaCl in this respect was capri- 
cious — sometimes decinormal solutions appeared to kill the 
organisms, sometimes not. Decinormal solutions of Nag CO 3, 
CaCl^, and BaCl^, were very injurious to Opalina, 
the two latter causing almost immediate disintegration, 
doubtless owing to their high stimulation efficiency causing 
excessive lowering of the surface tension. Decinormal KOH 
killed all the species and caused disintegration, doubtless, 
again, on account of its high stimulation efficiency. 
The galvanotaxis of these organisms was also tested. The 
ordinary stim.ulation trough, with parallel sides of porous 
clay, described by Verworn,^' was employed, and non-polaris- 
able brush electrodes were used to lead in the current. The 
following results were obtained . — 
1. Rectum of a frog left in tap water overnight. Some 
of contents placed in -— KCl in the stimulation trough and 
left for a quarter of an hour. Then tested with three tv/o-volt 
storage cells. Opalina all dead. Species B numerous^ their 
rotatory movements became slower and tended towards the 
kathode. In ten minutes the anodic half of the trough was 
deserted, and the kathodic half well populated, especially near 
the kathode. 
2. Some of contents of same rectum placed in ^-CaCL 
^ 10 ' 
for a quarter of an hour. Opalina all dead. Species B 
numerous. Tested with three two-volt storage cells. Organ- 
isms proceeded with an irregular, wavy motion towards the 
anode, and in a few minutes had formed a small cluster there, 
which remained unaltered. Several individuals, however, le- 
mained in the kathodic. half of the cell. 
3. Rectum left forty-eight hours in tap water. Some of 
X 
contents placed ni --Na^CO., and left for half an hour. 
Tested with ten two-volt storag-e cells. Organisms scanty, con- 
sisting of Opalina and species B. Both to kathode, the attrac- 
tion of species B being hampered by its rotatory movenioiiLs. 
In half an hour a small cluster had formed at tha kathode. 
* Verwom : General Physiology : Tnans. by Frederic S. Lee. 
page 416. 
