BOTANY: A. R. C. HAAS 
689 
The methods of kiUing the tissue were various. Sea water containing 
anesthetics (made up to the conductivity of sea-water by the addition 
of concentrated sea-water) was employed in many of the experiments. 
In this case the respiration was determined for several periods of equal 
length in sea- water (the solution being renewed after each period). The 
sea-water was then replaced by sea-water containing anesthetic and the 
respiration determined after successive equal periods until death ensued, 
and for some time thereafter. 
As it was important to know the time of death as accurately as pos- 
sible, determinations of the electrical conductivity of the tissue were 
made by the method of Osterhout.^ If the electrical resistance of the 
normal tissue be called 100% it is found that on killing the resistance 
falls to about 10%. When the resistance has fallen to 15% the tissue 
is for all practical purposes dead, as there is no recovery when it is re- 
turned to normal conditions. 
It was found that with sea-water approximately saturated with 
ethyl bromide the rate of respiration was about doubled. After the tis- 
sue v/as dead (as shown by the electrical resistance) it continued to 
respire for some time at a rate above the normal. Somewhat similar 
results were obtained when the sea-water contained 17.4% of acetone 
(by volume) and was made up to the conductivity of sea-water by the 
addition of concentrated sea- water. In this case the post-mortem rate 
of respiration is far above the normal and remains so for about 2 hours 
after the death of the tissue. This is also the case with sea- water con- 
taining 24% (by volume) of ethyl alcohol (the solution being made up 
to the same conductivity as sea-water). 
With sea-water which contained 3.2% formaldehyde, (the free acid 
neutralized with sodium carbonate and the solution made up to the 
conductivity of sea- water) it is found that at the end of 100 minutes 
after the electrical resistance shows the tissue to be dead, the rate of 
respiration has fallen to normal (before this time the rate is much above 
the normal). 
Experiments were made to ascertain whether different methods of 
killing would give different results. Tissue was exposed to running 
tap water for 19 hours (which was longer than was required to kill, as 
was shown by the electrical resistance) . After the exposure, the respi- 
ration rate was too small to be detected. It is probable that in this case 
the rise and decline of the rate of respiration was completed before the 
end of 19 hours. 
The respiration of another lot of material was determined before and 
after killing by means of exposure to a large volume of sea-water at 
