TENTH ANNUAL MEETING, 69 
third of its weight, and if only one foot of the frog be immersed 
in it, the blood globules can be seen to leave the vessels and dis- 
tribute themselves under the skin. If an animal be taken whose 
skin is not so absorbed, the same results appear in its bronchial 
system. When salt water fishes die from sudden introduction 
into fresh water endosmosis takes place, which is about the same 
thing under a reversed condition—the body of the fish contain- 
ing a denser fluid than its new medium. If the slime be removed 
from a fish its death will be accelerated when the change of 
water is made. This is illustrated by the eel, which can bear 
these sudden changes 1f uninjured, but if a portion of its pro- 
tecting mucous coating be removed, its skin becomes absorbent 
of the surrounding medium and it dies. The eel, which seems 
at home everywhere, puzzled M. Bert in a curious manner, but 
in the end confirmed his theory He had already experimented 
with them in changing fresh water ones into salt water, and 
found that they were indifferent to the change, and, wishing to 
continue his experiments, he directed his assistant to introduce 
the fish and report the results. To his great surprise the eels died 
after being three or four hours in salt water, and a long search 
failed to show why it was that they lived when he placed them 
there, and died when his assistant did so. Finally he found that 
on account of the eels being so slippery his assistant had used a 
cloth in handling them and rubbed off their slime, while M. Bert 
used his wet hands to which very little adhered. Osmosis had 
occured in the denuded portions and the eels died. Observa- 
tions on introducing sea fish into fresh water producad analogous 
results. The gills were the seat of alterations, the same as those 
‘noted in the fresh water fish ; and he observed that the life of 
sea fish could be prolonged after the change by adding: salt, 
which also tended to confirm his views. 
The shad, which passes so much of its life in the sea, cannot 
live there when first hatched. The experiments conducted by 
Prof. Milner and others, by direction of Prof. Baird, at Noank, 
Conn., in 1874, while I was on the way to Germany with young 
shad, showed that the newly hatched fish soon died under a 
gradual addition of sea water. My shad starved to death on the 
tenth day, as we reached England, and as it was impossible, and is 
