Vol. X. No. 247. 



THE AGRICULTURAL NEWS. 



331 



of locomotion, make their way from one citrus tree to another, 

 or to a second or third tree away. But the number thus 

 travelling would be exceedingly small, as compared with the 

 total. These records were made on soil with an ordinary 

 mulch. Tests were made on their powers of travelling over 

 compact soil, and they invariably showed very much greater 

 progress. A compacted irrigation furrow enabled even the 

 young red scale to travel two or three feet, while in a loose 

 mulch this scale makes practically no progress. The young 

 red scale, in attempting to ascend a small particle of earth, 

 falls back again, and this is repeated time after time. The 

 same is almost as true for the young purple scale. Where 

 there is a fine mulch, therefore, the chance of the young red 

 or purple scale reaching an adjoining tree is practically 

 negligible.' 



FERMENTED MILK. 



There has recently lieen much interest in the use of 

 various forms of fermented milk in certain diseases, and even 

 for the alleged purpose of retarding the changes that take 

 place in the human system on the approach of old age. This 

 interest has led to a consideration of the whole matter by the 

 Bureau of Animal Industry of the United States Department 

 of Agriculture, and the consequent issue of Circular 171 of 

 this Bureau, from which the following abstract has been made. 



Fermented milks are formed by an acid fermentation in 

 which lactic acid is produced from the sugar in the milk, the 

 process being brought about by bacteria, or when alcohol is 

 formed as well, by bacteria and yeasts together. The 

 preparations of fermented milk are usually introduced 

 from Southern Russia, Turkey and neighbouring countries, 

 and are sold as specially prepared milk, or in the form of 

 tablets or powders in capsules; the latter may be either 

 taken directly, or added to milk, in order to produce the 

 required fermentation. 



When dealing with the claims made for fermented milks, 

 it should be remembered, first of all, that they possess a high 

 food value, though this is sometimes reduced below that of 

 ordinary milk by the partial or complete removal of the fat. 

 As is well known, Metchnikoft' has put forward the opinion 

 that the lactic acid in such milk is capable of controlling 

 putrefactive changes in the intestine.s, and thus prolonging 

 life by the prevention of the action on the body of the dele- 

 terious substances that are produced by such changes. In 

 support of this, attention is drawn to the fact that those 

 peoples using fermented milk are generally long-lived. Their 

 longevity may, however, be due to the fact that such races 

 ustially follow a healthy outdoor life, and employ a simple 

 diet. These healthy conditions are themselves sufficient 

 to reduce the amount of auto-intoxication, or self-poisoning, 

 that is the result of the undue accumulation of poisonous 

 substances arising from putrefactive changes in the intes- 

 tines. The evidence of the production and absorption of 

 such substances often consists in an uncomfortable feeling of 

 indigestion and headache; the so called ptomaine poisoning 

 may even be caused. 



In considering the facts, it must be realized that, 

 while the digestive tract of human beings is normally free 

 from bacteria at birth, these soon gain access and under ordin- 

 ary conditions remain harmless and probably in some cases 

 aid dige.stion. It is of interest that the bacteria producing 

 autointoxication are anaerobic, that is to say they cannot 

 grow in the presence of air; while the harmless kinds can 

 live either with or without air. The theory of the action of 

 ■fermented milk as a remedy for auto-intf.vication is that the 

 introduction of lactic acid bacteria causes conditions to arise 



in which the poison-producing bacteria can no longer exist. 

 There is nu doubt that an improved state of health often fol- 

 lows the exhibition of fermented milk, and cases of this are 

 on record. The action may be due to the power of the lactic 

 acid in the milk to reduce the activities of the putrefactive 

 bacteria, or it may arise from the growth in the intestines of 

 bacteria that are capable directly or indirectly of suppressing 

 the other forms. As far as the first of these sU'.;gestions is 

 concerned, it is well known that many bacteria cannot grow- 

 in an acid medium. It must be remembered, however, that 

 the normal condition of the intestinal contents is alkaline, 

 and that any large increase of the acidity would interfere 

 seriously with the digestion. As a matter of fact, it does 

 not appear to be probable that the acidity of any kind 

 of fermented milk is sufficient to inhibit bacterial 

 activity. With reference to the second suggestion, namely 

 the introduction of acid-forming bacteria which multiply 

 at a great rate in the intestines, the evidence that 

 such a condition can be made to arise is by no means 

 conclusive It is in relation to this that the claims for 

 the possession of large acid-forming qualities is made for the 

 micro-organism that has come to be known as the Metchnikoff 

 bacillus, the bacillus of Massol, or Bacillus hulgaricus. In- 

 vestigations in connexion with this organism have given 

 conflicting results and, in the words of the Circular: 'It 

 must be admitted that up to the present time the investiga- 

 tions have not conclusively demonstrated that it is possible to 

 establish the lactic acid bacteria in the intestines with any 

 permanency.' In regard to other observations, indications 

 have been received that fermented milks may possibly 

 contain substances posse.ssing an antiseptic action in regard 

 to certain bacteria, so that the ingestion of these controls the 

 development of the latter. 



In concluding the discussion of the claims made for 

 fermented milks, it is stated that, although exaggerated 

 claims have been made for such milk, there is no doubt that 

 their use has been followed in many cases by an improve- 

 ment in health. It is probable that this improvement results 

 from the change in diet which their employment entails, and 

 in any case, before it is decided to consume large quantities 

 of such milk, the opinion of a medical man should be taken 

 as to whether this is advisable under the given circumstances. 



The following information concerning the various forma 

 of fermented milk is abstracted from the Circular: — 



CULTURES IN TABLET .\NJ) c.\PSULE FORM. These are 

 sold in addition to the fresh forms of fermented milk, and 

 are claimed to be pure and active cultures of Bacillus 

 hulgaricus. The examination^^f several preparations has 

 shown that this claim is by no means always justified. An 

 easy method of testing the purity aufl activity of such dried 

 cultures is to keep about half a pint of milk in a bottle closed 

 with cotton wool, at or near the boiling point, for at least an 

 hour, to let this cool, and then to adtl two or throe of the 

 tablets. The milk is then kept at a temperature near blood 

 heat for a night, when if Bacillus Indgaricus is present, it 

 will have curdled, with a sharp acid taste and the formation 

 of whey. 



BUTTER-MILK. This is obtained by churning milk 

 or cream for butter-making; it is often, however, sittlply 

 sour skimmed milk in which the curd has been broken 

 up by churning or stirring. Directions are given in the 

 Circular for various preparations of butter-milk. 



OTHER FORMS. These are Kelir (from the Caucasus), 

 Kumiss (from European Ru.ssia and Central and South 

 Western Asia), and Yoghurt (from the countries Iiordering 

 on the eastern Mediterranean). For interesting details con- 

 cerning these, reference is made to the Circular, . 



