120 INTERNAL SECRETION 



the same litter ; their bones were remarkably soft ; they had a 

 peculiar straddling walk; and they had not lost their milk-teeth. 

 There was no enlargement of the testicles. 



The implantation of the thymus in young dogs was followed 

 by contradictory results. The continued subcutaneous injection 

 of an extract of the thymus glands of sheep, produced in sheep a 

 backwardness in development and in weight. Ranzi and Tandler 

 assert that when applied to the enucleated eye of frogs, thymus 

 extract produces enlargement of the pupil. 



With regard to the influence of thymus extirpation upon the 

 nervous system, Basch (1908) proved that, in young dogs, the 

 well-known galvanic excitability of the peripheral nervous system 

 is distinctly increased after extirpation of the thymus. In animals 

 before thymectomy, or in control animals of the same age, the 

 kathodic closure contraction takes place at i to 2 milliamperes, 

 the kathodic opening contraction at over 5 milliamperes ; after 

 thymectomy, the kathodic opening contraction figures gradually 

 fall, reaching their lowest, 3 to 4 or even i .5 to 2 milliamperes, in 

 the third week, and at this they remain for several weeks. In two 

 cases there was an increased irritability at the cortex of the 

 brain of the motor-points affecting the anterior extremities. 



The hypersensibility of the nerves to electric stimulus is less 

 intense after thymectomy than after thyroparathyroidectomy, and 

 for this reason only a small proportion about one-tenth of 

 thymectomized dogs die of convulsions. 



According to Sabatini, and his view is confirmed by Basch, 

 in normal animals the direct application of soluble calcium salts 

 reduces the irritability of the cortex of the brain ; in thymectomized 

 animals, the subcutaneous injection of these salts produces a 

 distinct reduction of peripheral hyperirritability, and their re- 

 peated injection may even restore the kathodic opening contraction 

 to its normal figure. 



In normal animals, the injection of thymus extract is believed 

 to increase the sensibility of the peripheral nerves ; in 

 thymectomized animals, both thymus extract and suprarenal ex- 

 tract rather reduce this sensibility. 



According to Basch, the thymus gland is physiologically 

 associated with a definite reaction of the motor apparatus to the 

 electric current. He is of the opinion that the causative factor 

 of infantile tetany lies, not only with the parathyroid glands, 

 but with the entire group of branchiogenic organs, of which the 

 thymus is probably the most important; for not only is it very 

 sensitive in its reaction to general disturbances, but it is / 

 functionally active in the first years of life only. 



Now that we know that, in many species of mammals, the 

 thymus gland contains accessory parathyroids (Pepere), it seems 

 probable that the latent tetany associated with Basch 's experi- 

 ments was purely parathyroprive in origin, and not in any 

 way due to suppression of the function of the thymus. 



