808 THE ENDOCRINE ORGANS, OR DUCTLESS GLANDS 



this autacoid. The function of these two parts will therefore be con- 

 sidered together. 



Function of the Anterior Lobe, The facts concerning the function 

 of the pars glandularis have been gleaned largely by observing the ef- 

 fects produced by partial or complete removal of the entire pituitary. 

 Justification for ascribing the results of this operation to removal of the 

 anterior lobe, rather than to removal of the posterior is furnished by 

 control experiments in which removal of the posterior lobe alone failed 

 to produce similar effects. 



Complete removal of the pituitary is almost invariably fatal, the con- 

 dition being called apituitarism. Two operative procedures have been 

 employed for the removal of the gland. One of these, originated by 

 Paulesco and elaborated by 'Gushing and his pupils, 48 consists in trephin- 

 ing the skull and elevating the temporal lobe of the cerebrum so as to 

 expose the gland. The other, elaborated by Horsley, 49 consists in ap- 

 proaching the gland through the orbital cavity. Although there is some 

 danger of injury to nervous tissues by the intracranial method, its re- 

 sults are more dependable since the gland is actually exposed to view 

 before being removed. 



Most hypophysectomized animals die within two or three days, unless 

 they are very young. This longer survival of young animals is ascribed 

 to the presence of accessory pituitary material situated in the dura mater 

 lining the sella turcica. The most extensive observations have been made 

 on dogs. On the day following the operation the animal appears about 

 normal, but it gradually becomes less active, refusing food and respond- 

 ing slowly to stimulation. It gradually gets weaker and weaker; muscu- 

 lar tremors may appear, the respiration and pulse become slow, the back 

 arched, the temperature subnormal; and, usually within about forty- 

 eight hours, coma develops and the animal dies in this condition. Symp- 

 toms of equal severity ensue if the anterior lobe alone is removed. When 

 the symptoms are less acute and death does not occur so early, it is be- 

 lieved by Gushing either that small portions of the gland have been left 

 behind or that some vicarious activity of other organs has developed 

 to replace that of the pituitary. 



When only a part of the pituitary is removed either unintentionally 

 or intentionally, the symptoms are not nearly so acute, provided that 

 the portion remaining includes tissue of the anterior lobe. The condition 

 is known as hypopituitarism. It is by a study of this condition that 

 most facts concerning the function of the anterior lobe have been 

 learned. When the operation is performed on young animals, they 

 fail to grow properly ; the milk teeth and the lanugo are retained ; 

 the epiphyses do not ankylose; the thyroid and thymus glands are en- 

 larged; and the cortex of the suprarenal and the sexual organs fails to 



