CHAPTER XVIII 

 THE PITUITARY BODY 



The late Professor Haldane once said that anatomy, if studied 

 with inteUigence, can be as important as physiology in the investi- 

 gation of function. In this chapter I hope to be able to convince 

 my readers that this is possible ; if the pituitary body is studied 

 with a definite object in view, results can be obtained without the 

 aid of experimental biology, which are quite as convincing as many 

 physiological experiments. The only drawback to this method is 

 the length of time involved to get the required answer to the 

 problem set before the observer. Before describing the pituitary 

 body of the eel, which is the fish we have chosen to study, we may 

 state that it is known that in vertebrates, this gland produces 

 hormones (chemical messengers) that have a great influence on the 

 generative organs, and these are known as gonadotropic hormones ; 

 it is further known that certain changes take place in the gland, 

 as shown by the staining reactions of certain cells, when these 

 hormones are producing their effect. 



Now the eel, as is well known, puts on its wedding dress, which 

 is evident when it changes from the yellow eel to the silver eel, 

 and its eyes become larger and its flesh becomes firmer, when it is 

 about to migrate and start on its marvellous journey to its breeding 

 ground. These changes do not take place in the British Isles as a 

 rule until the end of the summer or the beginning of autumn. 

 Now it occurred to the writer, as the result of certain findings as 

 totheappearanceof the gland when sections were examined, which 

 did not tally with textbook descriptions, that the differences noted 

 might be due to the different periods of the year, at which the fish 

 had been taken. This proved to be the case and it was decided to 

 make a systematic series of examinations of the pituitary of the 

 eel, commencing in the spring and going on month by month until 

 the end of October, or the beginning of November. These ob- 

 servations were carried out during a period of two years, and it was 

 very definitely shown that marked changes took place in the micros- 

 copic appearance of the gland in September and October ; and it 

 was further shown that these changes took place before the ovaries 



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