40 PHYSIOLOGY CHAP. 



of the various organs of these animals in search of possible 

 modifications. The glandular part of the hypophysis proved to 

 be considerably larger in volume, with bigger follicles, and more 

 colloidal substance in the interfollicular spaces. This led him to 

 conclude that in rabbits the hypophysis might supplement thyroid 

 deficiency. 



The experiments of Rogowitsch were repeated and confirmed 

 by Stieda (1890), Hofrneister (1882), Gley (1892), and others. 



Tizzoni and Centanni (1890) observed the same facts in three 

 dogs that long survived total thyroidectomy as Rogowitsch had 

 noted on rabbits, and came to a similar conclusion. Schonemann 

 (1892) adduced the results of clinical observation in support of 

 the same thesis, and demonstrated a hypertrophy of the pituitary 

 body in cases of goitre, when a great part of the parenchyma of 

 the thyroid gland does not function. These observations, although 

 contradicted by Schwarz, have recently been confirmed by Corute. 



This theory of a close relation and functional substitution 

 between the thyroid and the hypophysis was shaken by the work 

 of Vassale and Sacchi, and of Caselli, while the later observations 

 of Gaglio on amphibia (1900), and of Lo Monaco and Van Ryn- 

 berk in our laboratory (1901) on dogs, proved that the syndromes 

 brought forward to support it are not the necessary and direct 

 consequences of loss of the pituitary body. 



Moreover, Luzzatto, working in Coronedi's laboratory on the 

 hypophyses of animals that long survived the total ablation of 

 the thyro-parathyroid apparatus, never succeeded in finding any 

 morphological indication of hypertrophy of the pituitary body 

 from exaggerated function. 



The same negative results were obtained by Friedemann and 

 Maass in Germany, and more recently by Dalla Vedova (1903) in 

 the Institute of Surgery in Rome. Thus, whatever may be the 

 function of the pituitary body, we now know that it is not of 

 sufficient importance for its complete ablation necessarily to 

 bring about the death of the animal, provided the technique 

 is satisfactory. 



Nor did Cyon's experiments (1898-1902) lead to more 

 positive results. Starting from his work on the thyroid he 

 assumed that the hypophysis co-operated with this organ in 

 maintaining equilibrium of endocranial pressure, founding his 

 theory upon the alterations of pressure consequent on injections 

 of pituitary extract obtained by various methods. It may be 

 remarked that the results of various experimenters as to the 

 role of the supposed active principles of the pituitary gland 

 differ widely. According to Szymonowicz (1898) pituitary 

 extract diminishes blood pressure and accelerates the pulse: 

 Schafer and Swale Vincent (1899) say that it raises blood pressure ; 

 Mairet and Bosch (1896), that 'it excites the nervous system; 



