114 SCIENTIFIC REPORTS OF THE AGRICULTURAL RESEARCH 



of the pebrine spore under varying natural conditions; this 

 point seems to require elucidation as a necessary prelimin- 

 ary to such enquiries as the one above referred to, and the 

 success of antiseptic measures would largely depend upon 

 their having been devised with due knowledge of the resist- 

 ance of the resting stage or spore form of the parasite to 

 natural antagonistic or destructive agencies such as desic- 

 cation or heat. 



Progress in experiment on this subject is necessarily 

 slow for various reasons. Firstly must be taken into 

 account the fact that no means is at present known of deter- 

 mining either the vitality or the infective power of this 

 protozoal parasite except by the success or otherwise of 

 experimental infection of its natural host; this at best 

 requires several weeks to show any positive result, and in 

 any case may fail to do so from causes other than loss of 

 infective power or vitality by the parasite, such as unduly 

 high resistance of individual hosts, making it necessary to> 

 use large numbers of the latter to eliminate this source of 

 error as far as possible. Numerous other disturbing fac- 

 tors have to be allowed for such as the possibility of acci- 

 dental infection from adventitious causes either in the- 

 worms under experimental infection or in the controls. 

 Further work on the purely protozoological side of the ques- 

 tion is required before absolute knowledge of this part of 

 the problem can be obtained, and this in my opinion must 

 be carried out, and carried out in India, before it will be 

 possible to advance in actual practice much beyond the pre- 

 sent empirical stage of treatment. 



So far I have been able to ascertain with some certainty 

 a few important points with regard to the persistence of 

 vitality of the infective organism, amongst which may be 

 mentioned the interesting fact that desiccation for as much 

 as six months did not destroy the infective power of the 

 pebrine spore, whereas moderate moisture at the same tem- 

 perature rendered it innocuous in one month. It will be 

 obvious that more complete knowledge of this sort would 

 be invaluable in introducing an}^ modifications in existing 

 practice, especially those depending upon avoiding certain 



