DECEMBER 24, 1897. ] 
of the fats. But they throw very little 
light upon the proteid metabolism. 
For the succeeding twenty-four days the 
dosage was raised to twenty tablets a day. 
The effect was unmistakable. The nitro- 
gen eliminated was 4% in excess of that 
contained in the food. The loss of weight 
amounted to 2.25 kilos, or nearly five 
pounds, and at the close of the period the 
animal was so thin that its ribs and pelvic 
bones showed plainly. When, however, the 
nitrogen loss (in all 30 grams) is multi- 
plied by the figure 30, which Pfluger has 
shown to represent the ratio between the 
proteid tissues and their nitrogen content, 
it is evident that the albuminous waste can 
account for only three-sevenths of the total 
loss of weight. The other four-sevenths 
(in all three pounds) must have come from 
the fats, which implies an increase of com- 
bustion to the extent of 483%. The violent 
panting of the animal points to the same 
‘conclusion ; while the loss of nitrogen shows 
that, just as is the case during prolonged 
hunger, when the supply of fat has been re- 
duced to a certain limit, the system falls 
back upon its proteids to meet the demands 
caused by iodothyrin. 
At this point the administration of thy- 
roid tablets was stopped, and contrary to 
the statements of some observers, that iodo- 
thyrin has a considerable after-effect, the 
nitrogen balance became positive immedi- 
-ately and the body weight increased rapidly. 
When the animal had again attained its 
normal weight, the investigation was re- 
peated. Twenty tablets a day were ad- 
ministered. The animal’s weight fell a 
pound a week. For the first few days the 
nitrogen in the excreta exceeded that in the 
food by 8%. But the daily analyses 
showed that by the twelfth day nitrogen 
‘demand and supply were again in equi- 
librium. 
At the end of two months, however, the 
weight ceased to fall. The tablets were 
SCIENCE. 
949 
discontinued for a week, and the weight 
rose one and a half pounds. On adminis- 
tering the tablets again for two weeks the 
weight fell one and a half pounds, but the 
nitrogen maintained a steady plus balance. 
From these facts Schondorff concludes 
that in the case of an animal at a uniform 
weight and in nitrogenous equilibrium iodo- 
thyrin causes an increase of combustion 
and a consequent loss of weight. So long 
as the store of fat is above a certain limit 
proteid metabolism, however, remains un- 
affected; the temporary minus balance of 
the body’s nitrogen is due to an increased 
elimination of urea and similar substances 
which existed pre-formed in the tissues; 
but when the fats have been reduced below 
a certain limit the proteids are likewise at- 
tacked. Throughout his investigations, 
however, Schondorff assigns all the effects 
produced to the iodothyrin contained in the 
ingested thyroids. He accepts the prevail- 
ing opinion of physiologists, that the iodo- 
thyrin isolated by Baumann is the full 
physiological equivalent of the gland, and 
at no time during the research was the pure 
substance administered in place of the 
glands. Yet experiments by Dr. Hdm. 
Wormser, published in a later number of 
Pfliger’s Archiv (Band 67, p. 505), seem 
to show that the thyroid itself oran aqueous 
extract of the gland possesses a physiolog- 
ical activity (at least when fed to animals 
whose thyroids have been removed) far in 
excess of that exhibited by pure iodothyrin. 
Similar results have been obtained by A. 
Schiff, who has been working at this ques- 
tion simultaneously, though quite independ- 
ently. (Wiener Klin. Wochenschr. 1897, 
p. 277.) Schiff, however, states that differ- 
ent preparations of iodothyrin vary con- 
siderably in the extent fof influence they 
exert, but he asserts that no preparation 
shows a physiological activity at all com- 
parable to that of the gland itself. If later 
researches verify these observations they. 
