CARCINOMA OF THE THYROID IN SAEMONOID FISHES. 435 
Table V.— Incidence of Thyroid Carcinoma in Wooden Troughs, Craig Brook, 1910-1912. 
Trough 
No. 
Lot No. 
Date. 
Age. 
Species. 
Total 
fish. 
Visibly 
affected. 
Visible 
tumors. 
Loss. 
y^'ears. 
Number. 
Per cent. 
Per cent. 
Per cent. 
2034 
j 
Tulv. loii 
2 
do 
3 .^ 
65- 7 
20. 0 
40. 7 
94 
2036 
Aug., 1910 
I 
Hybrid trout, 5 brook, cf saibliiig 
86 
. 0 
. 0 
July, 1911 
2 
do 
77 
26. 0 
i '3 
10. 0 
Aug., 1912 
3 
do 
6o 
48.3 
3*3 
22. 0 

2081 
. 6 
July, 1911 
2 
do 
173 
5 - 2 
.6 
50.0 
Aug., 1912 
3 
do 
135 
26. 6 
• 7 
21. 9 
2033 
85 
July, 1911 
2 
do 
66 
25 - 7 
9.0 
22.3 
Aug., 1912 
3 
do 
62 
43 - 5 
19-3 
6.6 
2037 
5. 8 
July, 1911 
2 
do 
39 
35-9 
2- 5 
62. I 
Aug., 1912 
3 
do 
28 
50. 0 
14. 0 
28. 2 
nn 
87 
July, 1911 
2 
do 
23 
17. 4 
13*0 
73- 5 
Aug., 1912 
3 
do 
II 
54- 5 
i 3 . 0 
52. I 
2080 
898 
lOI. 
2 
. 6 
Aug., 1912 
3 
do 
303 
I. 0 
. 0 
8.7 
205sB 
\ 
July, 1911 
2 
do 
60 
61.6 
38.3 
[ (“) 
Aug., 1912 
3 
do 
47 
91- 5 
34 ' 0 
1 
'' 
July, 1911 
2 
do 
95 
21. 0 
3- I 
53- I 
Aug,, 1912 
3 
do 
76 
43-4 
6.6 
20. 0 
July, 1911 
2 
do 
64 
59-3 
9-3 
7- I 
Aug., 1912 
3 
do 
53 
70. 0 
17.0 
17. I 
« Many fish used in experiments. 
LAKE AUBURN HATCHERY, MAINE. 
This is a State hatchery in Androscoggin County. In August, 1910, an examination 
of fish for visible tumors was made and the general conditions inspected. Pond i was 
a dirt pond fed by two springs of water very cold at its origin, and standing at 11° C. 
in the pond*on August 20. The spring water has a very low content of dissolved matter 
and is said to have about the same analysis as the well-known Poland Springs; of Maine. 
The pond held nearly 400 brook trout of 3^ years of age, which had occupied the pond 
since the yearling stage. They had been fed raw beef liver until a year old and raw 
beef heart ever since. The fish were raised from eggs from the local station and from 
domesticated eggs obtained from Michigan. They were apparently in fine condition, 
were feeding well, and had suffered but little loss. One hundred and thirty-one of these 
trout were examined, of which 20.5 per cent showed visibly diseased thyroids and 5.3 
per cent of the 131 bore visible tumors. 
Pond 2 was a similar dirt pond, fed from six independent springs and sometimes 
by the overflow of pond i. Its water was warmer, being 15.5° C. It held 4-year-old 
brook and brown trout and adult landlocked salmon. A seine haul of fish were exam- 
ined. Of 66 brook trout, 21.5 per cent had visible tumors and 19.5 per cent red floors; 
of 15 salmon, i had a red floor and 4 had visible tumors; of 36 brown trout all were 
entirely clean, without external sign of thyroid proliferation. The food was beef heart. 
There was no marked mortality rate, but there was a heavy loss on spawn taken from 
the fish of this pond. 
