LOUPING-ILL. / o 



By comparing the photo-micrographs with the microscopic 

 drawings, both by Dr. Hunter, published in my article on 

 Louping-Ill in 1882,^ it will be observed that the similarity, if 

 not identity, is maintained throughout. From the long and 

 exhaustive investigation (in which I have been assisted by my 

 son, W. 0. Williams, and Dr. James Hunter, and to whom my 

 thanks are due) of this disease, I am now more convinced than 

 ever that the organism or organisms are most probably developed 

 in one stage as minute moulds on old grasses — in this condition, 

 innocuous to the higher animal, nntil it has passed through the 

 tick ; that in the body of the tick it attains properties which 

 are virulent when subsequently communicated to the sheep by 

 the tick. 



It will be observed that in the louping-ill organism there are 

 met with, during its complete life history, those involving 

 series of transitions assumed by G. Zopf and other bacteriolo- 

 gists to be more or less presented during the development of 

 many micro-organisms. Leaving it, as most have done, to 

 be decided whether or not the forms seen in such cases as 

 the present are the exact counterparts of saprophytes, typical 

 micrococci, bacteria, or bacilli, there is no doubt that such 

 variations are seen during the growth of the louping-ill organism. 

 But further, when it has been found that the inoculation of 

 healthy animals by certain of these forms has led to the appear- 

 ance of the others in great constancy under varied conditions, 

 the identity of a series of forms can no longer be disputed. It 

 must, however, be confessed that as yet the true relationship 

 and significance of the individual forms have not been so fully 

 made out as could be wished from a purely biological point of 

 view ; but the pathogenic action peculiar to the organism has, 

 by all the usual modes of research, been placed beyond cavil. 

 This is not to be wondered at, when it is remembered that 

 several well - known micro - organisms have stages in their 

 development that are by no means fully understood. Appar- 

 ently the simple unsegmented saprophytic filaments are 

 generally met with in the spinal myxoedema of the affected 

 animal, while the higher forms of spore filaments, fully seg- 

 mented and free rods, closely resembling the typical bacillus, 

 were seen, so far as the present observations go, mostly in culti- 



^ See Transactions of the Highland and Agricultural Society. 



