THE PITUITARY 359 



the former may bear a causal relation to the latter. The 

 effects are more marked in males than in females. 



In very few of these investigations (the last -mentioned series 

 forming a notable exception) has sufficient attention been paid 

 to the difference between the anterior and posterior lobes of 

 the pituitary. It must be pointed out that, even when ordinary 

 care is taken to separate the anterior from the posterior lobe, 

 the former will include a strip, which varies in thickness in 

 different animals, of the pars intermedia. The reflection of 

 this part over the nervous portion is now well known, and 

 account has been taken of its presence in the consideration of 

 the effects of posterior lobe extracts (see Section D ), but the fact 

 which I have just pointed out, viz., that there is a reflection of 

 the pars intermedia over the anterior lobe, is not so generally re- 

 cognized (Fig. 94) . If the pars intermedia be traced round from 

 the nervous on to the glandular portion, it will be noticed that 

 the cells forming it gradually fuse with the cells of the glandular 

 portion in the depth of the latter structure, but are continued 

 as a layer, retaining at any rate some of the characters of the 

 pars intermedia, along the edge of the cleft. Although the 

 amount of pars intermedia adhering to the anterior lobe is not 

 very considerable, it is possible that it might make a difference 

 to the physiological extract. 



Houssay is the only author, so far as I am aware, who has 

 definitely drawn this as a continuation of the pars intermedia ; 

 though Herring states that the anterior lobe in the cat is 

 separated from the cleft by cells, " which are larger than endo- 

 thelial cells," and are continuous at the anterior and posterior 

 ends of the cleft with the cells of the epithelial reflection. He 

 admits too that the cells of the intermediate portion occasionally 

 spread down a little over the front of the anterior lobe. The 

 general arrangements are shown in Fig. 94, and the microscopi- 

 cal structure in Fig. 95. 



Pituitary feeding is stated to have very similar effects to 

 those produced by thyroid in bringing about precocious meta- 

 morphosis in amphibia. It is also said that the rate of fission 

 of planarian worms is increased by a diet of pituitary substance. 



G. Grafting Experiments 



The effects due to increased functional activity of the pit- 

 uitary body cannot be induced by glandular transplantation. 



