SERUM DIAGNOSIS OF ECHINOCOCCUS 359 



stage ; the hooks of Tcvnia echinococcus are plump, sharply curved, 

 and have a short posterior root process the length of which is to that 

 of the total length as i to 4*7, whereas on the contrary the hooks of the 

 alveolar echinococcus are more slender, slightly bent, and have a 

 long posterior root process (i to 2-5) ; and (5) on the form of the 

 uterus, which in the alveolar Taenia has the form of a spherically 

 distended sac anteriorly. 



SERUM DIAGNOSIS OF ECHINOCOCCUS. 



(1) Precipitin Reaction. Mix equal parts of hydatid fluid (of the 

 sheep) and serum of patient. Keep at 37 C. The reaction is not 

 decisive as it may be given by normal sera. 



(2) Complement Deviation. Required : (i) Hydatid fluid of sheep 

 (antigen), (2) guinea-pig complement, (3) patient's serum, (4) red 

 cells of sheep, (5) haemolytic serum (of rabbit) against sheep's red 

 cells, (6) 0*8 per cent, salt solution. Mix the antigen + patient's 

 serum (heated) -f- complement + salt solution at 37 C. for one hour. 

 Add red cells of sheep + haemolytic serum. Allow to stand for 

 half an hour at 37 C. It is imperative to make adequate control 

 observations. An example will indicate the method. Salt solution 

 i'3 c.c. + patient's serum (heated) 0*2 c.c. + hydatid fluid 0*4 c.c. + 

 complement 0*1 c.c. of serum diluted to a quarter strength + haemo- 

 lytic serum and red cell emulsion i c.c. Result : no haemolysis, i.e., 

 the patient's serum contains specific (echinococcus) antibodies. 



