Capillary glass tubes are either cylindrical or furnished with a bulbous expansion at the middle, the latter form being most commonly used. To charge a tube make sure that both ends are open, and then submerge one end in the pool of lymph. Capillary attraction will cause the tube to fill, and the process may be facilitated materially by inclining the tube toward a horizontal direction, so that the capillary attraction is not opposed by that of gravitation. Care should be taken to keep the applied end of the tube constantly submerged, or bubbles of air will enter it. The sealing may be done with a blowpipe, by simply holding the ends in a flame, or by means of sealing-wax or some similar substance. The satisfactory charging of tubes demands some practice, but a little patience will enable any intelligent person to succeed.
In regard to crusts, they should never be removed until the surface beneath has become cicatrized and they have been partially detached by the natural process. A crust torn off prematurely should never be used, and the same may be said of secondary crusts—i.e. those that form by the desiccation of the discharge from the raw surface left when the primary crust has been removed forcibly.
For the preservation of vaccine in these various forms tubes need only be kept in a cool place. Dried lymph and crusts should be guarded against dampness even more than against warmth. Their preservation may be decidedly favored by over-drying, either in an exhausted receiver or by keeping them in a closed vessel in the presence of sulphuric acid, chloride of calcium, or some other substance having a strong affinity for water. It is needless to say, however, that they should not come into actual contact with any such agent. While this artificial desiccation tends powerfully to preserve dried lymph, it makes it more difficult to use. When dried lymph or a crust is to be sent by mail or other conveyance, it should be wrapped in some impermeably envelope, for which purpose gutta-percha tissue is very convenient. Both these forms of virus should be kept in a cool place. There is no objection to keeping them on ice, provided they are well protected against moisture.
In conclusion, the writer wishes to say that the limited space at his command has compelled the assumption of a dogmatic rather than an inductive form in the construction of this article. To the reader who may wish to pursue the subject further—and it will well repay thorough study—he would recommend the following bibliography:
Ballard: On Vaccination: its Value and Alleged Dangers, London, 1868.
Bousquet: Nouveau traité de la vaccine et des éruptions varioleuses, Paris, 1848.
Bryce: Practical Observations on the Inoculation of Cow-pox, Edinburgh, 1809.
Ceely: Observations on the Variolæ Vaccinæ, Worcester, 1840.
Chauveau et al.: Vaccine et Variole, Paris, 1865.
Depaul: Nouvelles recherches sur la véritable origine du virus vaccin, Paris, 1863; De l'origine réelle du virus vaccin, Paris, 1864; et al.: De la syphilis vaccinale, Paris, 1865.