PRACTICAL EXERCISES 531 



are the most marked symptoms. The animal must be weighed daily, 

 the temperature taken in the rectum, the thermometer being always 

 pushed in to the same distance ; and it will also be well to determine 

 the number of the red corpuscles in samples of the blood. To 

 obtain the samples punctures may be made in the gluteal region with 

 the point of a narrow-bladed knife or lancet, the skin having been 

 first shaved and thoroughly dried. The blood should flow freely 

 without pressure (p. 61). A record of the experiment from the 

 operation to the autopsy must be kept. At the autopsy search must 

 be made to see whether the thyroid was completely removed, and 

 whether any accessory thyroids exist. Such are occasionally found 

 in the form of small reddish masses, either in the neck or within the 

 chest in the neighbourhood of the aorta. If any are found, they 

 must be hardened in alcohol and sections made. Portions of the 

 muscles, spleen, and central nervous system are also to be preserved ; 

 and it is to be observed whether the pituitary body has undergone 

 any increase in size or other change (pp. 485, 489). 



6. Thyroidectomy with Thyroid Feeding. Some of the members 

 of the class should modify experiment 5 by feeding the animal, as 

 soon as symptoms have appeared, with fresh sheep's thyroid glands 

 or commercial thyroid extracts, and noting any alleviation of the 

 symptoms. If, as only rarely happens, they disappear, the animal is 

 to be allowed to live for a considerable time, then killed by chloro- 

 form, an autopsy made, and portions of the tissues hardened and 

 compared with those from experiments done as in 5. 



342 



