CULT I RINC. FAECES. 265 



Soaps are gnarled bodies everted like the pinna of an ear, while 

 soap crystals are comparatively coarse and do not melt on application 

 of gentle heat as do the more delicate fatty acid crystals. Neutral 

 fat is in round or irregular globules. The best stain for fat is Sudan 

 III (saturated solution of Sudan III in equal parts of 70% alcohol 

 and acetone). 



Mix up the faeces with dilute alcohol (50 to 70%) and then add a 

 drop of the above solution and apply a cover-glass quickly. The fat 

 globules show as orange or golden-yellow bodies. Much connective 

 tissue debris shows defect in gastric digestion, as only the stomach 

 digests connective tissue. 



In examining a liquid stool after salts, it is well to color the drop of 

 faeces, which is to be covered with the cover-glass, with a small loopful 

 of 1/2% solution of neutral red. If diluting fluid is used, it should be 

 salt solution, and not water. The neutral red tinges the granules of 

 the endoplasm of amoebae and flagellates a very striking brown-red color, 

 thus differentiating them from vegetable cells or body cells. 



Whether examining the thin faeces or the mucus particle, it is well 

 to reserve report on amoebae or flagellates until motion is observed. 

 Encysted protozoa are difficult to diagnose. 



When a smear preparation is desired, we may smear out a fragment 

 of mucus and stain by Romanowsky's or Gram's method. The charac- 

 ter of the bacteria present appears to be of diagnostic value especially 

 in the case of infants and young children. Beautiful preparations may 

 be made by mixing the faeces with water, then centrifuging for one 

 minute. This throws down vegetable debris and crystals. Now 

 decant the supernatant fluid, which holds the bacteria in suspension, 

 and add an equal amount of alcohol. Again centrifuge, decant, and 

 smear out and examine the bacterial sediment. Gram's method, with 

 dilute carbol fuchsin counterstaining, gives the best picture. 



To culture for typhoid, dysentery, cholera or other bacteria, take 

 up the material in a tube of sterile bouillon and smear it out with a 

 swab over a lactose litmus agar plate or an Endo or Conradi-Drigal- 

 ski plate. Before streaking the plates they should be very dry on the 

 surface. This can be best done by pouring into a plate with a circular 

 piece of filter-paper in the lid and placing in the incubator for one-half 



