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Well-made silage is a succulent yellowish materialwith a slightly acid taste and a faint but pleasantsmell. Its food value depends on how and fromwhat it is made. Ordinary silage, on a dry-matterbasis, has a food value equal to hay, but molassedsilage made from young leafy grass may containtwice the protein of hay and rival a cake or otherconcentrated food. Silage and hay are not in factinterchangeable in stock dietetics, but are rather

complementary, the silage adding succulency to theanimals’ diet. Normally silage contains more caro-tene than hay, and in late January, when milk andbutter lose their colour and with it much of theirvitamin-A content, the feeding of good silage willensure that the consumer gets a milk rich in vitaminat a time when other protective foods are scarce.

Moreover, though Hitler may try to fire our hay-stacks he will find it difficult to destroy silage withhis incendiary bombs.

Annotations

FITNESS FOR SERVICE

Boys mostly leave the elementary schools in good con-dition. Physical training under the Board of Educationis an everyday part of their lives, well organised andwell taught. After the age of fourteen they have tofend for themselves and get what exercise they can.

Many of them, lacking the stimulus and competition ofcompanions, become physically lazy, and as Lord Dawsonhas pointed out (Times, July 8), " the promise of child-hood too often fades away into weediness and futility."It seems deplorable that we need a war to drive thislesson home-that we, who pride ourselves on humandealing, should never have ensured for our youngercitizens the chance to achieve full growth. In a leadingarticle the Times (July 4) noted that the Fitness forService scheme has evoked a comparatively poorresponse. The Central Council for Recreative PhysicalTraining and the Football Association have worked hardto provide quarters and instructors, but attendances havenot been large, and the mixed bag of those attending-ranging from tired munition workers to energetic youthsof seventeen-has complicated the task of those incharge. Lord Dawson suggests that the difficulties canbe overcome by dividing those to be trained intogroups. Boys between 15 and 18 should receive com-pulsory physical training under the joint direction of theBoard of Education and the War Office, the board beinglargely responsible for the younger and the War Officefor the older boys. The War Office should also havethe task of providing trained instructors. Munitionworkers, he thinks, should be spared violent physicalexertion at the end of a long day, and should ratherbe restored with music, dancing and the drama. Disabledor wounded men form a third group requiring specialtraining under medical supervision. This aspect of thework might well be left to the direction of the doctorsabetted by the Chartered Society of Massage and MedicalGymnastics. Rehabilitation is a complex process whichcan hardly be fitted into a general fitness campaign.If a system of widespread physical training for youngpeople can be arranged now perhaps it is not too muchto hope that it may be maintained when peace comes.Fitness for service is an ideal worth keeping before usin peace as well as war.

ONE-SHOT DIPHTHERIA IMMUNISATION

DESPITE its obvious administrative advantages the prac-tice of immunising against diphtheria by a single injec-tion of alum-precipitated toxoid has not found general,favour in this country. Clinical experience and experi-

mental work both support the vital part played by asecond injection in producing the highest level of lastingimmunity. Nevertheless the one-shot method has notbeen without success, particularly where there is a reason-able degree of basal immunity, a fact which ledSaunders 1 to suggest that it would be the best wayof affording rapid and widespread protection in urgentcircumstances. A somewhat similar view has recentlybeen expressed by a committee of the American PublicHealth Association,2 who, although preferring the two-dose method, yet consider that, in the face of practicaldifficulties, it is better to give a single injection ofA.P.T. to a large number of children than two doses tohalf as many children. Clearly if all susceptible childrenwere so immunised it would only require a 70% Schickconversion-rate to deal effectively with a particular epi-demic of diphtheria. Whether an immunity so inducedwould be lasting is, of course, another matter. On anotherpage Dr. Farago also demonstrates the superiority oftwo injections in promoting maximum immunity, buthe has been able to test over 20,000 children who forvarious reasons received only a single injection of A.P.T.1-5 years previously. Even allowing that the 86°5a/oSchick-negative rate he obtained was artificially raisedby the inclusion of natural immunes (no preliminarySchick testing was done), it remains an impressive figurewhen applied to the numbers involved. Doubtless it hascontributed in no small measure to the decreased incidenceand death-rate for diphtheria in Hungary in recent years.In this success Farago takes full account of the partplayed by latent infection and is prepared to revisehis opinion as to the sufficiency of one-shot immunisationif basal immunity is found to decline in the future. Itis to be deplored that we in this country can quote nocomparable experience. Certainly nothing but large-scale experiments under varying conditions can decideon the efficiency or otherwise of any particular methodof mass immunisation. For the individual it appearsto be our duty to offer the highest level of protectionobtainable and this necessarily involves two injections ofA.P.T. at suitable intervals.

JAM WHEN SUGAR IS SCARCE

THE sugar in jam performs four functions: it sweetensit, preserves it, helps it to set and adds to its bulk. Nosubstitute can do all this, and if we are to make jamwithout sugar we must add more than one substance totake its place. Saccharin will do the sweetening, thoughit does not taste quite the same as sugar, and is sufficientlyheat-stable; roughly 25-30 grains is equivalent to a poundof sugar. Preservation can be attained either by asepsisor antisepsis. In the aseptic technique, which is

employed in bottling fruit, the pots are sterilised by heatbefore use and melted paraffin wax is poured on the topof the jam as soon as it is put into them; alternativelyair-tight screw-capped jars can be employed. With thistechnique the jam will not keep well when it is unsealed,and small pots should be used. Antisepsis is complicatedby the law, which prohibits the addition of any preserva-tive t jam except sulphur dioxide in a strength of 40parts per million. This does not affect the flavour of thejam but is also unlikely to affect the growth of mouldsand bacteria. If the jam is not going to be sold we mayuse more powerful preservatives such as benzoic or sali-cylic acid, and these are perfectly safe if carefullyweighed. Gelatin will make the jam set and will alsoadd to its bulk, though unfortunately it encourages thegrowth of moulds. The pectin preparations which aresold to help soft-fruit jam to set do not work withoutsugar.The Good Housekeeping Institute have lately carried

out some experiments for THE LANCET based on these1. Saunders, J. C. Lancet, 1937, 1, 1064, and 1940, 1, 390.2. Report of the subcommittee on evaluation of administrative

practices of the American Public Health Association. HealthNews, April 8, 1940.