*2-2 THE DUCTLESS GLANDS 



therefore easily mistaken for it in the course of the operation. 

 Bearing all these difficulties in mind, the present writer and 

 Professor Jolly did not hesitate to declare that, except in very 

 favourable cases, where the internal parathyroid chances to lie 

 near the surface of the thyroid lobe, the operation is an impos- 

 sible one. The injury caused to the thyroid in endeavouring 

 to excavate an almost invisible body from its substance, com- 

 bined with the accompanying profuse haemorrhage, may account 

 for some of the deaths which other experimenters have attri- 

 buted to parathyroid insufficiency. It will be obvious that the 

 other operation viz., to remove all the thyroid tissue, while 

 leaving the parathyroids with their blood-supply uninjured 

 is still more difficult, and it was not attempted, though it was 

 found possible in some cases to leave one or two external 

 parathyroids. 



The animals upon which the experiments were performed 

 were cats, dogs, foxes, monkeys, rats, guinea-pigs, and rabbits. 



Ten out of fifteen cats on which the total operation was 

 performed, either at one or more times, died soon after, the 

 respective periods of survival varying from three to thirty-four 

 days. Five survived the operation. Of the animals which 

 survived, three showed grave nervous symptoms as the result 

 of the operation. The fourth, which was a young cat, ceased 

 for a time to grow, while remaining otherwise perfectly normal. 

 The fifth showed no symptoms. On what theory are we to 

 account for the exceptions to the rule that death rapidly 

 follows the complete operation ? These exceptions are fairly 

 numerous, and they have also formed a conspicuous feature of 

 previous investigations. The presence of accessory thyroid or 

 parathyroid tissue suggests itself as a probable explanation, 

 but it must be borne in mind that a careful post-mortem 

 dissection of neck, thorax, and even abdomen, failed to disclose 

 such bodies. 



The symptoms usually following the complete operation 

 in the cat are as follows : The cat is perfectly well on the day 

 following the operation ; on the second day, there is usually 

 a curious " paw-shaking " and some malaise. This is followed 

 in rapid succession by tremors, stiffness of gait, and convul- 

 sions. Even in a quiescent state, the fore-legs tend to be flexed, 

 while the hind-legs are extended, a position exaggerated during 

 convulsions. Hallucinations are fairly common. Of symp- 



