32 
It seems unnecessary to divide the functions of the tlryroid into 
“metabolic” and “ detoxicatory,” as is sometimes done. It is suf- 
ficient to recognize that the thyroid has certain effects— for the most 
part unknown — upon metabolism. Under normal conditions these 
effects lead to the formation of useful substances or promote in other 
ways cellular activities. When an unusual poison, such as acetonitrile, 
is introduced into an animal under the influence of thyroid, its fate will 
depend upon how the animal’s metabolism as regards this poison has 
been affected by the thyroid; the latter alters the metabolism of the 
mouse in such a way that the acetonitrile is rendered harmless or is 
prevented from becoming harmful, but it alters the metabolic pro- 
cesses of rats and guinea pigs in such a way that the acetonitrile 
becomes much more harmful. In a somewhat similar way certain 
processes of oxidation proceed along definite lines ; for instance, when 
a poison such as ethyl alcohol is introduced into the body these 
processes of oxidation destroy it, thus not only making it harmless, 
but the body is enabled to utilize the energy set free. In the case of 
methyl alcohol, however, although the oxidation may proceed along 
similar lines, part of the alcohol is converted into substances (formal- 
dehyde and formic acid) more poisonous than the original substance. 
The fate of acetonitrile in the body of a mouse to which thyroid has 
been administered may be compared to the fate of ethyl alcohol; 
that of acetonitrile in the body of a rat which has received thyroid 
to that of methyl alcohol. 
i. EXPERIMENTS WITH ‘ 1 IODINE FREE” THYROID.® 
The question whether thyroid free of iodine has any physiological 
activity has, like the entire question of the relation of iodine to the 
thyroid, been approached from two points of view. Those who have 
considered it from the standpoint of the activity of a living gland in 
a By “iodine free ” thyroid we mean thyroid which does not give even a qualitative 
test for iodine when 1 gm. of sample is examined by the Baumann method. The 
limit of this method when applied to a complex body like the thyroid, which contains 
a very large amount of organic matter, is about 0.01 per cent; although somewhat 
smaller amounts of iodine could be satisfactorily estimated by using more than 1 gm. 
of material. As is well known, Paul Bourcet (Compt. rend. Acad. d. sc., Par. 1899, 
128 , p. 1120) modified the Baumann method so that very much smaller amounts 
of iodine could be determined when 50 to 1,000 gms. of the material were employed. 
The modification consists in concentrating the solution of the fused mass obtained by 
the incineration of the sample and removing the potassium sulphate by repeated 
precipitation with alcohol. By this method Bourcet was able to estimate as small an 
amount as 0.1 mgm. of iodine per kilogram of sample. A. R. Dochez (Johns Hopkins 
Hospital Bull. 1908, 19 , p. 235) using this method, found iodine in crystallized cane 
sugar, egg yolk, “C. P. glucose,” and in a very large number of other ordinary foods. 
Of the substances examined only C. P. lactose, egg albumen, chocolate, almonds, and 
pig embryos (thyroids excised) were reported as containing no iodine. 
It is very probable that the thyroid which we call “iodine free” would have been 
found to contain iodine if examined by Bourcet’s modification, and it is also possible 
