456 
BUIvI^ETlN OE THE BUREAU OF FISHERIES. 
Of 30 wild trout injected in the thyroid region with 2 minims each of tumor 
ground with an equal volume of salt solution, about half died from the immediate toxic 
effect of the injection. At another trial one-tenth cubic centimeter of material made 
from several tumors was injected into each of 15 domesticated trout. Eleven of them 
succumbed almost immediately. The material was then diluted until it contained 3 
volumes of salt solution and 15 more fish were injected, but 12 of these died within 2 or 
3 hours. Seven fish were injected subcutaneously near the dorsal fin with one-fifth 
cubic centimeter of this material, and 5 died within a short time. One cubic centimeter 
was, however, passed into the stomach of i trout, and one-haE cubic centimeter each 
into the stomachs of 3 others without apparent effect. This particular sample of com- 
bined tumor substance was unusually toxic. 
The trout dying from the immediate physiological effect of trout tumor substance 
ground with salt solution showed a fairly characteristic picture of symptoms, ending in 
tetany. The mechanical effect is little, as shown by the control fish. In the few 
cases where the shock from trauma is apparent the fish lies on its back or side, scarcely 
breathing, and recovers in a few seconds. The inoculated fish, however, were evidently 
poisoned. They became immediately distressed, swam in circles or in short, frantic, 
and aimless dashes about the trough, then fell greatly weakened upon their sides and 
lay there with short and rapid breathing until the next paroxysm. Finally they suc- 
cumbed in tetany, some with gills widely distended and marked opisthotonos. Even 
the survivors seemed to be much weakened. 
Forty-three wild brook trout were inoculated in the thyroid region with small 
portions of tumor taken directly from the fish without grinding or mixing with salt 
solution. Pieces were forced through the floor of the mouth by means of trochar, probe, or 
seeker. The material was more or less toxic even in this form, and the mechanical injury 
and bleeding were greater than with the needle, but 24 of the 43 trout survived. 
Ten domesticated brook trout were injected in the thyroid region with one-fifth of a 
cubic centimeter each of a mixture of one volume of domesticated brook trout blood 
and three volumes of physiological solution. No loss attended the operation, and the 
fish have never shown any but the immediate reaction to the inoculation. 
In all injections and inoculations the instruments used were sterile, and the tumor 
material obtained as free from contamination as possible. It is not usually possible to 
obtain in quantity the thyroid tumor material from fish in a completely aseptic condition. 
Mud from one of the fish ponds (no. 10) constantly associated with tumor fish was 
injected into the stomachs of 25 domesticated trout and of 20 wild trout. The dose 
was repeated on the former lot after three days. The filtrate of this mud through paper 
was injected into the thyroid region of 25 domesticated trout and behind the eyeball 
of 17 domesticated trout. The dose was 2 to 2^ minims. These fish have shown no 
results from the inoculations. 
Trout tumor material has been ground with sand and filtered through a Berkfeld 
filter. The filtrate has been injected into the thyroid region of 2-year-old domesticated 
trout, all manipulations being carried on in the cold. About 0.3 to 0.4 cubic centimeter 
of filtrate was given each of 9 trout. These were kept under observation for over four 
