294 THE CASE AGAINST EVOLUTION 



wild and weird speculation was originally inspired by the 

 false assumption that the hypophysis was a functionless organ. 

 As a matter of fact, it is the source of two important hor- 

 mones. The one generated in its anterior lobe is tethelin, a 

 metabolic hormone, which promotes the growth of the body in 

 general and of the bony tissue in particular. Hypertrophy 

 and overfunction of this gland produces giantism, or acro- 

 megaly (enlargement of hands, feet, and skull), while atrophy 

 and underfunction of the anterior lobe results in infantilism, 

 acromikria (diminution of extremities, i.e. hands, feet, head), 

 obesity, and genital dystrophy {i.e. suppression of sec- 

 ondary sexual characters). The posterior lobe of the pituitary 

 body constitutes, with the pars intermedia, a second endocrine 

 gland, which generates a stimulatory hormone called pituitrin. 

 This hormone stimulates unstriated muscle to contract, and 

 thereby regulates the discharge of secretions from various 

 glands of the body, e.g. the mammary glands, bladder, etc. 

 Hence the hypophysis, far from being a useless organ, is an 

 indispensable one. Moreover, it is an integral and important 

 part of the cryptorhetic system. 



The same story may be repeated of the thyroid glands. 

 These consist of two lobes located on either side of the wind- 

 pipe, just below the larynx (Adam's apple), and joined to- 

 gether across the windpipe by a narrow band or isthmus of 

 their own substance. Gaskell homologized them with a gland 

 in scorpions, and Mathew says that, if his surmise is correct, 

 ''the thyroid represents an accessory sexual organ of the in- 

 vertebrate." {Op. cit., p. 654.) They are, however, endo- 

 crine glands, that generate a hormone known as thyroxin, 

 which regulates the body-temperature, growth of the body 

 in general, and of the nervous system in particular, etc., etc. 

 Atrophy or extirpation of these glands causes cretinism in the 

 young and myxoedema in adults. Without a sufficient supply 

 of this hormone, the normal exercise of mental powers in 

 human beings is impossible. The organ, therefore, is far from 

 being a useless vestige of what was formerly useful. 



