310 National Vaccine Establishment. 



lymph, though originally pure, which has been injured by 

 long keeping, by heat, or otherwise. Or they maybe caused 

 by performing the operation with rusty or unclean lancets, 

 or in a rude manner, or by injuring the vesicle at an early 

 stage, and thereby exciting too much inflammation, or in- 

 terrupting the regular progress of the disease. Herpetic 

 eruptions, and other cutaneous affections have also been 

 supposed the cause of these irregularities, and occasionally 

 to prevent the vaccine lymph having any effect. 



The Methods of taking Vaccine Lymph for Vaccination. 



The lymph of a regular vesicle is efficacious from the 

 time it is secreted, till the areola begins to spread. It 

 may therefore commonly be taken till the ninth day j but 

 not after the areola is. formed. 



The lymph is to be taken by small superficial punctures 

 made in the vesicle with the point of a lancet. Time should 

 be allowed for the liquid to exude, which will form small 

 pellucid drops. When requisite, a very slight pressure may 

 be cautiously applied with the flat surface of the lancet. 

 Great delicacy is requisite in this operation ; for if the ve- 

 sicle is rudely treated, or too much opened, inflammation 

 and ulceration may ensue. 



Lymph intended to be used immediately, or in a few 

 days, may be received on a lancet ; but this is an improper 

 instrument for preserving it longer ; for the lymph soon 

 rusts the lancet, and it is then liable to be inefficacious or 

 injurious. (Quills and toothpicks succeed; but small bits 

 i of ivory shaped like the tooth of a eomb, and properly 

 pointed, are the most convenient instruments; and to ren- 

 der them more certain, they should be charged repeatedly. 



In order to preserve lymph for a long period, the best 

 method is by two bits of square glass. The lymph is to 

 be received on the centre of one of them, by applying it to 

 a punctured vesicle. When fully charged and dry, it is to 

 be covered with another bit of glass of the same size, and 

 wrapped up in paper or in gold-beater's skin. 



In whichever way the lymph is taken, it should be al- 

 lowed to dry without heat in the shade, and be kept in a 

 dry and cool place. When inclosed in a letter, if great care 

 is not taken, it may be injured by the heat of the melted 

 wax in sealing the packet. 



The Mode of Vaccinating. - k 



Liquid lymph is better than dry, because it seldomer fails, 

 and the operation is more lightly and quickly performed. 

 Therefore, in every instance where it is practicable, the pa- 

 tient 



