September 17, 1920] 



SCIENCE 



275 



ance of the tadpoles to infection. In each 

 case the portion transplanted is placed in a 

 pocket under the skin above the right eye. A 

 delicate knife made from a needle ground to 

 a cutting edge is used in making the pocket 

 into which the piece of material is thrust. 



The chief aim of these experiments is to 

 study the several functions of the different 

 portions of the hypophysis. It is quite easy 

 to separate the anterior lobe from the other 

 portions but the intermediate and posterior 

 lobes are tightly applied together although 

 the difference in texture makes it quite easy 

 to distinguish them. In a large portion of 

 the experiments these lobes were both trans- 

 planted together. In other series they were 

 laboriously dissected apart and separately 

 transplanted. 



The experiments show in clearest fashion 

 that each part functions quite differently 

 from the others. 



1. The anterior lobe transplanted to normal, 

 to pituitaryless, and to thyroidless tadpoles in 

 each case produces a marked acceleration of 

 growth so that the tadpoles thus treated are 

 conspicuously larger than those into which 

 the other parts of the hypophysis have been 

 transplanted. They are larger than normal 

 controls and larger than controls into which 

 muscle tissue has been transplanted in the 

 same way and at the same time as the above 

 operations. 



The anterior lobe also produces a marked 

 acceleration in the development of the hind 

 legs. This happens to be most conspicious in 

 the pituitaryless specimens probably because 

 they were the first operated; but at the date 

 of writing — June 14th — the same appears to 

 be true of the normal and the thyroidless 

 specimens into which this lobe has been trans- 

 planted. The white pituitaryless tadpoles into 

 which this lobe has been transplanted show not 

 the slightest tendency to return to the orig- 

 inal black color except for a slight temporary 

 tendency at the beginning. This may be due 

 to the adhesion of particles of the inter- 

 mediate lobe or to a certain amoimt of secre- 

 tion that had diffused from the latter. It 

 soon clears up however. 



2. Normal tadpoles into which the inter- 

 mediate lobe is engrafted become much more 

 darkly colored than the controls, while those 

 which have been made to turn white as a 

 result of removal of the anlage of the hypo- 

 physis exclusive of the posterior lobe are 

 made to change back from white to black 

 when the intermediate lobe is engrafted into 

 them. There is not the slightest doubt that 

 this lobe is responsible for the conspicious 

 color changes controlled by the hypophysis. 

 This return to the black color takes place 

 slowly, being scarcely completed inside of ten 

 days. Specimens into which the intermediate 

 and posterior lobes together have been trans- 

 planted show this phenomenon of deepening 

 of the black pigmentation as well as those 

 into which the intermediate lobe alone has 

 been engrafted. 



3. Tadpoles into which the combined inter- 

 mediate and posterior lobes are transplanted 

 show not only the color change mentioned 

 above but they also suffer a marked con- 

 traction of the body walls. Within twelve 

 hours they appear very emaciated. This char- 

 acteristic gradually disappears, in the course 

 of ten days. These tadiwles show apparent 

 retardation of growth. When the intermediate 

 and posterior lobes are dissected apart and 

 transplanted separately it is seen that this 

 phenomenon is wholly due to the posterior 

 lobe. It is probably caused by the well-known 

 property that this portioti of the hypophysis 

 jKJSsesses for bringing about muscular con- 

 traction. The details of this will need further 

 study. The posterior lobe does not produce a 

 restoration of the black color to pituitaryless 

 tadpoles. 



In summing up it may be said that although 

 we have not taken the pars\ tuberalis into ac- 

 count and can not make a complete analysis 

 of the functions of the different parts of the 

 hypophysis until we do, the following conclu- 

 sions are justified. 



1. The anterior lobe of the hypophysis 

 stimulates growth and metamorphosis. 



2. The intermediate lobe is very largely if 

 not wholly concerned in regulating such color 

 changes as are controlled by the hypophysis. 



