PUNCTURE OP THE THORAX. 



503 



used. The so-called aspirator (Fig. 387) consists of a rubber tube, 

 hollow needle, and large syringe provided with a two-way tap. The 

 hollow needle is inserted into the chest, the piston raised, and when 

 the syringe has become full, the exit cock is opened, and the contents 

 discharged. The process is then repeated. The aspirator, however, 

 has been little used in veterinary surgery. The same object is more 

 easily attained by pushing one end of a suitable rubber tube over 



Fig. 



387.— Dieulafoy's aspirator, with handle for introducing the needle and 

 flexible connection for syringe. 



the free opening of the cannula, and dropping the other end into 

 water. This syphon-like arrangement exerts an aspirating action 

 on the contents of the thorax, but has the disadvantage that the 

 outflow cannot be exactly controlled, while forcible aspiration may 

 rupture pleural vessels. 



While using the ordinary instrument, if it be required to check 

 the outflow of fluid, and especially if excitability, dyspnoea, and 

 coughing set in, the trocar must be removed.^ The necessity of 



