632 LABORATORY HINTS 



A yeast attacks tlie milk sugar after lactic acid has been formed, 

 inhibits the gro\\th of pathogenic and putrefactive bacteria and im- 

 proves tiie taste. The yeast may get the upper hand and carry the 

 fermentation too far. 



Pathogenic ycasls cause blastomycetic dermatitis as sometimes seen 

 in man. 



They have also been recovered from tumours, lung diseases, sprue 

 and dysentery cases. 



To Stain Yeasts. 



Use Gram or an}- :?imple stain. 



Remember that they stain mahogany brown and not gentian violet 

 with Gram. 



THE EXAMINATION OF F.ECES. 

 MACROSCOPIC. 



This is a very necessary routine practice in the tropics. 



Note the number, bulk, colour, odour, consistency and the reaction 

 of the stools. 



Note the presence or absence of gaseous fermentation. 



The presence or absence of blood, mucus, pus and their degree of 

 admixture whh the stool. 



Any visible £inimal parasites, undigested food materials, &c. 



Remember that mucus from the small intestine is stained with bile 

 and is not frequent) \' seen, but mucus is common from the lower bowel 

 and may be caused by anything tliat sets up inflammation in it such 

 as bilharzia, chronic ulcerations as from ulcerated haemorrhoids, 

 nic'ilignant and granulomatous gro^\•ths and chronic dysentery. 



In acute dysentery the mucus is usually clear, not mixed with 

 faecal matter, and may be streaked with bright red blood. 



If it comes awa}- in condensed hard masses with much debris and 

 epithelial tissue ^\ith pus the affection is usually of the rectum. 



If bowel casts are passed (membranous colitis) they may be twisted, 

 these should be floated out in water as they may resemble worms. 



If bright red blood is passed it does not necessarily mean that it 

 has come from tiie rectum, such mav come from the small intestines. 



If the stools are numerous, pale, frothy, it is suspicious of sprue. 



Remember that in the tropics the caecum and upper part of the 

 colon may be ulcerated acutely and extensively without passage of 

 either mucus or blood or with tenesmus. Such may be rapidly fatal. 



Remember that rice and plantain eating peoples pass much larger 

 stools normally tlian do meat eating peoples. The people of the East 

 eat excess of carboh^-drate food to obtain sufBcient protein. 



