542 PHYSIOLOGY CHAP. 



brought to light some very interesting phenomena, which indicate, 

 however indefinitely and incompletely, the functional importance 

 of this organ. 



Kestelli (1845) was the first who attempted extirpation of the 

 thymus on lambs, dogs, and calves, without, however, obtaining 

 any practical results. Friedleben (1858) resumed the experiments 

 with better success. He succeeded in keeping alive several dogs 

 on which lie had operated by excising the thymus alone, or the 

 thymus and spleen together. He did not, however, pay much 

 attention to the age of the animals on which he was experimenting, 

 nor did he undertake comparative experiments under perfectly 

 comparable conditions. In the animals deprived of their thymus 

 he noted increase of water in the blood (hydraemia), increase of 

 leucocytes (leucocythaemia), and diminution of erythrocytes (oligo- 

 cythaemia) ; conspicuous reduction in the carbonic acid given off 

 in the time unit ; general trophic disturbances, particularly in the 

 bony, and also in other tissues. He concluded that the thymus is 

 not an organ indispensable to life, although it is highly important 

 shortly after birth, since during the development of the body it 

 promotes nutrition, formation of the blood, and also, therefore, of 

 the tissues. Nothing was added to these results in a short paper 

 published by Langerhans and Savaliew (1893). 



At the International Medical Congress in Eome (1894) Tarulli 

 and Lo Monaco communicated the first results of their experiments 

 as performed in our laboratory, which were subsequently completed 

 and published in a larger memoir. 



By means of the Thoma-Zeiss method, they confirmed the fact 

 already stated by Friedleben, to the effect that dogs deprived of 

 their thymus exhibited a more or less pronounced state of anaemia, 

 consisting in a diminution of erythrocytes and increase of leuco- 

 cytes. They added, however, that this was only a temporary 

 effect, and that two or three months after the operation the 

 number of blood-corpuscles became almost equal to that of the 

 normal dogs born in the same litter. 



Puppies deprived of their thymus are stunted in growth, weigh 

 less, and have more flaccid muscles than the control animals. The 

 difference is especially conspicuous a month or a month and a half 

 after the operation ; later on it dies out gradually, and cannot be 

 detected after about three months. The hair differs both in length 

 and pigmentation in puppies with and without a thymus. Gener- 

 ally speaking the coat of the latter is rougher, without the normal 

 gloss and resistance, and yields to the slightest pressure. Sometimes 

 the bones of the limbs are longer, thinner, and more bowed in 

 puppies with no thymus ; sometimes there is an exaggerated 

 development of head at the expense of the rest of the body. 



Puppies with no thymus further show reduced resistance and 

 capacity for muscular work ; they seldom leave their bed, and are 



