growth of certain moulds or other resistent growths, which give off, in their growth, some chemical agent which is inimical to the vaccine virus The trial of all lymph, to test its activity prior to issue, would be the ideal procedure, but lack of sufficient children in the neighbourhood of the Institute, and the labour entailed, renders this difficult to carry out. In the case of Sind, only, it has been found feasible to await the result of a trial issue before despatching the remainder of that lymph number to Sind vaccinators. In this case it is essential, that a vaccine of the highest potency should be supplied, owing to the time taken by lymph packets in the post, before they come to the hands of the vaccinators, and also, owing to the very high temperatures recorded in Sind during the hot season. Therefore a preliminary trial issue is made to the Superintendent of Vaccination at Karachi, who sees, personally, the results obtained and at once advises us if the vesiculation is of goo d quality. In this way lymphs which do not prove resistent to these adverse conditions are identified and excluded from issue.
The Chloroform Process of Purification.
The removal of extraneous organisms from vaccine lymph, by the agency of chloroform vapour, was first introduced by Dr. A. B. Green7 of the Lister Institute in 1902.
His method was to triturate the pulp with distilled water, one part pulp to three water. Chloroform-saturated air was then blown through this emulsion for two hours. The inlet and outlet of the vaccine tube were then clamped, and the chloroform retained in the emulsion for 18 to 42 hours. A current of sterile air was then passed through the lymph and the chloroform partially removed. The lymph was stored in an ice-chest at 10" C. and, immediately before issue, the remainder of the chloroform was blown off and glycerine was added, in the proportion of two parts of glycerine to the original weight of the pulp.
He found that all the extraneous organisms were killed off by this method and that the vaccine virus was still active, so that the lymph was ready for despatch without prolonged storage.
Blaxall informed me that this method of Green's was given a thorough trial at Hendon, but that it proved injurious to the vitality of the lymph in some cases, and he would only recommend it, where lymph was required so urgently as not to permit of storage.
The method seemed to oiler great advantages in India, where the facilities for cold storage were very limited, and Hutchiiison carried out a
