526 PROTOZOA 



operating-room should be well lighted and provided with a table and 

 with stools. 



The only requisites for the table are that it should be heavy and firm ; 

 that it should have holes through the top so arranged that straps can 

 be passed through them to hold the calf down, and a vertical strip on 

 one side of the table to which the upper hind leg of the calf can be 

 fastened. The calf can be thrown upon the table easily by two attend- 

 ants. 



The laboratory should also be well lighted and furnished with tables, 

 chairs, desk, case for instruments, and refrigerator. It should also 

 have both a steam and a dry-air sterilizer, a set of scales weighing to 

 grams or centigrams, and a blast lamp and bellows. In stock there 

 should be one to two thousand bone slips for seed virus, and ten to 

 fifteen thousand smaller slips for issue; two or more scarifiers; a curette; 

 four to six razors for shaving the animals; a razor strop; a pair of large 

 scissors, curved on the flat, for clipping the animals; a burette, from 

 which glycerin flows while the vaccine pulp is being ground; burette 

 holder; a Doring vaccine grinder; clinical thermometers to take the 

 temperature of the animals; six to twelve small glass dishes with covers; 

 a hard-rubber syringe, of four-ounce capacity, to make suction ; absorb- 

 ent cotton; glass vials and corks; and several pounds of soft glass 

 tubing, three-eighths of an inch in calibre, to store virus emulsion. 

 There should also be gowns and caps for the attendants. Sodium 

 carbonate, bichloride of mercury, bromine for a deodorizer, alcohol, 

 and glycerin are the chemicals needed. 



For issue for public vaccinations there are also needed packing- 

 boxes, rubber bands, sheet wadding, needles, and wooden toothpicks 

 for removing the virus from the vials and rubbing it on the scarifica- 

 tions. 



Yield. The material obtained from the five children should vaccinate 

 at least five calves; it may easily vaccinate fifteen calves. Ten grams 

 of pulp and two hundred charged slips would be an average yield from 

 a calf, and that, when made up, should suffice to vaccinate at least 

 fifteen hundred persons. Calves vary immensely in the yield. Of two 

 calves vaccinated in precisely the same way one may furnish material 

 for five hundred vaccinations and the other for ten thousand vaccina- 

 tions. 



The Durability of. Glycerinated Virus in Sealed Tubes. As a result of 

 testing from time to time an immense number of specimens of vaccine, 

 the conclusion has been reached that vaccine properly put up should 

 keep at least three months. From time to time a single lot of virus will 

 fail by the end of one month. Sometimes this is due to the glycerin, 

 as when it has some chemical impurity, or as when simply it is not 

 diluted sufficiently with water. We find that one part of water to two 

 of glycerin makes a good dilution. 



Bacteria in Vaccine. It is impossible to prepare vaccine on a large 

 scale so that it is at the time of its removal free from bacteria. In fact, 

 there are usually very large numbers of one or more varieties of bacteria 



