490 
BULIvETIN of the bureau of fisheries. 
in size and form. At the center of the lobule where the degenerative changes are most 
outspoken are found large areas of desquamated cells with cloudy protoplasm, taking 
the stain deeply. The cell boundaries are not sharply defined, the nuclei generally 
smaller than in the preceding area, of varying size and deeply stained. Diagnosis; 
Diffuse hyperplasia of the thyroid gland with degenerative changes at the center and 
invasion of the capsule at the periphery. 
RATS. 
In 1910 and 1911 a prolonged attempt was made to affect the thyroid of rats by 
giving them water to drink from the fish ponds in which the disease was endemic. A 
barrel of water from pond 10 of the Craig Brook station and a quantity of mud from 
the same pond were shipped to Buffalo and kept in cold storage. A series of experi- 
ments were begun with young rats obtained from Granby, Mass. Each experimental 
lot consisted of 10 rats. The food was a mixture of corn, oats, sunflower seeds, and 
dog biscuit. The mud and water was administered daily to the separate lots as follows: 
1. Trout-pond mud; small quantities. 
2. Trout-pond mud; large quantities. 
3. Trout-pond water. 
4. Craig Brook water. 
5. Trout-pond mud; cooked. 
6. Trout-pond water; boiled. 
7. Trout-pond water, injected subcutaneously, followed by mud and water feeding. 
The feeding of the mud, water, etc., was continued with the same individuals for 
a period of about six months. A few were killed from time to time during this period 
for examination of the thyroid. Neither in these nor in those remaining at the close of 
the experiment were there any thyroid enlargements or any microscopic condition differ- 
ing materially from the controls. 
In the light of Bircher’s subsequent observations there are several reasons why 
these experiments might have failed. Bircher gives the following reasons why water 
may lose its goiter-producing qualities : (o) Water kept under conditions different from 
those of its origin for days or weeks; (b) water which before use has been continually 
shaken or has undergone a long trip by rail; (c) water to which small amounts of chem- 
ical agents have been added ; (d) that the agent is more active in the water in the sum- 
mer months and that the source frequently loses its activity in the winter. Three of 
these reasons bear on the possible negative nature of the above experiments, and as they 
are all made with water taken from ponds in which the agent is present in dilute form, 
it is quite clear that the length of time was not sufficiently great to produce positive 
results. These experiments must therefore be repeated with the animals at the source of 
water supply and continued over a period not less than 18 months. 
The pond water and mud having failed to produce definite changes in rats during 
six months under the experimental conditions, a quantity of scrapings from one of the 
wooden fish troughs (no. 102), in which thyroid tumors were constantly developed, was 
