MILK 211 



of bacteriology was necessary to supply the information on which 

 the rational use of this therapeutic agent is based. For the past 

 fifteen or twenty years medical journals have contained occasional 

 papers on fermented milks of various kinds, and at one time the 

 use of kumiss in the treatment of tuberculosis and other diseases 

 was much discussed. The present interest in the subject is largely 

 due to the work of Metchnikoff and his students. 



Fermented milks are now recommended when a nutritious and 

 digestible food is essential, but it is in the treatment of disorders re- 

 sulting from autointoxication that their chief value is supposed to 

 lie. Autointoxication may be caused by the undue accumulation 

 of poisonous substances which, are promptly removed in health. 

 Toxic substances usually found in small quantities may be produced 

 in excess, or, what is more common, toxins may be formed by bac- 

 teria in the intestines in amounts too great to be disposed of through 

 the usual channels. These toxic substances are absorbed into the 

 system and produce symptoms which may be merely an uncomfort- 

 able feeling of indigestion and headache, or which may assume the 

 more acute form frequently and erroneously spoken of as ptomaine 



Eoisoning. This form of autointoxication is usually accompanied 

 y intestinal gas and foul-smelling stools. One symptom 01 great 

 value to the physician is the excretion in the urine of abnormal 

 quantities of indican and ethereal sulphates. 



The Various Forms of Fermented Milk. If it is considered 

 advisable to use cultures of acid-forming bacteria, the form in which 

 these are taken becomes an important question. In large cities one 

 usually has a choice of lactic-acid bacteria from several sources. 

 Buttermilk is usually available, although it is not always of good 

 quality. Sometimes kumiss or kefir can be obtained, and at the, 

 present time milk coagulated with the so-called Metchnikoff bacillus 

 is sold as yoghurt or matzoon and under various trade names. 



Buttermilk. This, properly speaking, is the by-product result- 

 ing when milk or cream is churned for butter making. It is the 

 milk remaining after the fat has been collected in globules and re- 

 moved. If cream is churned when sweet the buttermilk does not 

 differ from ordinary skimmed milk, but if it is churned when sour 

 the usual practice the acidity is sufficient to coagulate the casein 

 in the cream. In the churning process this curd is broken up into 

 very fine particles. These curd particles settle very slowly, and if 

 the buttermilk is agitated occasionally it will retain its milky ap- 

 pearance. When the buttermilk is allowed to stand undisturbed for 

 several hours the curd particles sink to the bottom leaving an opal- 

 escent whey at the top. At the present time a large part of the but- 

 termilk sold in cities is not made by churning cream, but is simply 

 soured skimmed milk which has been churned or stirred in order 

 to break up the curd. The same product is sold also under the name 

 of ripened milk. 



The souring of milk or cream is brought about by the activity 

 of certain bacteria which form lactic acid by decomposing the milk 

 sugar (lactose). The ability to form acid from lactose and other 



