194 BOARD OF AGRICULTUKE. [Pub. Doc. 



Owen Clark, in Prattsville, just over the Revere line, either late in 

 July or early in August, 1902. By the latter part of August it had 

 spread to the premises of two or three of his neighbors, and thence 

 was carried to various points, where the disease prevailed during the 

 autumn and winter of 1902 and 1903. 



Prior to the time of the discovery and public announcement of 

 foot-and-mouth disease, the middle of Novembei', 1902, the New Eng- 

 land Vaccine Company of Chelsea bought the young cattle it used 

 for the production of vaccine ^'irus from Mr. Clark, who would buy 

 thrifty looking young cattle from various sources, and when they had 

 been used at the New England Vaccine Company's establishment 

 he would take them home to his place, where they w^ere kept for a 

 while, until he could dispose of them. 



The proprietor of the New England Vaccine Company states that 

 the vaccine virus produced there during the last three or four years 

 has retained its strength to a remarkable degree, ^nd that it has 

 not been necessary to introduce ncAV " seed," as is often done at 

 these establishments when the virus is found to be deteriorating; but 

 it has been his custom when inoculating animals to put in a couple 

 of " control " points of virus placed on the market by other pro- 

 ducers, in order to compare the quality of his with theirs, and to 

 be sure that his product was maintaining its standard of strength 

 as compared with others. 



During 1902 he i;sed the product of six different American manu- 

 facturers of vaccine virus, among others some from the same estab- 

 lishment from which Dr. Tyzzer's supply was obtained, Avhich was 

 used in the Wakefield experiments. 



During the summer of 1902 the proprietor of the New England 

 Vaccine Company was in Europe, and little Avas done at that estab- 

 lishment; but in order to keep the vaccine virus from losing its 

 vitality it was necessary for his assistant to inoci;late an animal 

 every month or six weeks, for the purj50se of carrying the supply 

 along at a standard strength. When one of these inoculations was 

 made, " control " points were also put in for comparison. It does 

 not seem unlikely that a heifer may have been inoculated in July, 

 and control points used which were contaminated with foot-and- 

 mouth disease virus, enabling the animal to convey the disease to 

 OAven Clark's premises either late in July or early in August, without 

 contaminating the vaccine Adrus produced by the Ncav England Vac- 

 cine Company, as it has been shown by Dr. Tyzzer's investigations 

 that the calves inoculated with a mixed vaccine and foot-and-mouth 

 disease a'ii'us did not shoAV easily recognizable symptoms of foot-and- 

 mouth disease, yet they Avere capable of producing it in an unmis- 

 takable form among the cattle with which they were kept. At least, 

 there is no historv to show that animals used later at the New Eng- 



