106 INTERNAL SECRETION 



for he found iodine in considerable quantities in the thyroid gland 

 of dogs which had, for months, been given food which contained 

 no halogens. If the thyroid furnished a continuous supply of 

 iodine to the blood, it would in time, under these conditions, part 

 with the whole of its supply. But, as Kraus points out, this 

 argument is not convincing, for, judging by the analogy of other 

 substances which are present in the organism in small quantities 

 only, it is by no means improbable that the iodine which leaves 

 the thyroid gland is again returned to it by the agency of the 

 blood-stream. Further, Baumann, and also Miwa and Stoltzner, 

 showed that, under conditions similar to those described by Blum, 

 the amount of iodine present in the gland is actually reduced. 



If Blum were right in his original assumption that the thyroid 

 gland supplies a vital principle to the blood-stream, we should 

 expect the ligature of the veins and lymphatics leading away from 

 the gland to be followed by symptoms of suppression. Not only is 

 this'not the case, but Blum found that this operation was followed 

 by an increased oxidation, a stimulated cardiac activity, 

 destruction of the red blood-corpuscles, and serious lesion of the 

 liver, the bile pigment passing into the urine. He deduces from 

 this that the ligature of the vessels leading away from the gland 

 causes obstruction, and consequent overflow, of its contents ; 

 that this produces a partial insufficiency of the organ, which gives 

 rise to appearances similar to those which follow the exhibition of 

 thyroid juice. But the results of these experiments contain no 

 proof that an incomplete, and therefore toxic, toxalbumin proceeds 

 from the gland. It is much more probable that, under the changed 

 circulatory conditions, which do not, however, completely arrest 

 the flow of blood from the gland, the amount of the normal active 

 substance which passes into the blood-stream is very much 

 reduced. 



That Blum was unaware of much that has recently been 

 discovered concerning the nature and function of the thyroid 

 gland, is suggested by the fact that he speaks of the parathyroids 

 as bodies composed of undeveloped thyroid tissue, which con- 

 tribute nothing of importance to the general economy. He draws 

 his conclusions from his own and Kishi's experiments with dogs, 

 which lived for a considerable time after extirpation of the para- 

 thyroids, a small proportion of thyroid tissue having been left 

 in situ. Blum describes the post-mortem findings as follows : 

 " After a certain time, the remains of the thyroid showed a 

 remarkable increase in the number of the interior cells, which 

 produced a certain resemblance to the parathyroids. The follicles, 

 with occasional isolated exceptions, had entirely disappeared, and 

 the colloid substance was absent. Closer investigation showed that 

 the cell-agglomerations formed a tubular structure, similar to that 

 seen in true glands." After a comparison of this description with 

 the plates reproducing the microscopic findings, it is not possible 



