246 p. MANSON ON THE PERIODICITY OF 



(I.) on July 26. Thirty grains were taken in three doses of ten 

 grains each at intervals of one hour, beginning at ten a.m. On the 

 following c'ay you see the pulse rose, the temperature fell, and com- 

 paratively few embryos could be found circulating, and their ingress 

 that evening appeared to be delayed ; but by one a.m. on the 28th 

 they were as numerous as ever, and thenceforward periodicity and 

 numbers continued as before the experiment. I cannot say, how- 

 ever, that this slight perturbation was the result of the quinine, for 

 Tiong-Seng (II.) was treated exactly in the same way on the 29th, 

 but periodicity and numbers were in no way affected. 



Nitrite of Amyl (15 drops) was inhaled by Li-Kha (I.) at ten 

 a.m. on the 25th. There were no embryos in the blood when in- 

 halation commenced ; shortly afterwards 2 were found in one 

 slide — 3 at one p m., 2 at four p.m., at seven p.m., 18 at ten 

 p.m. 



Sontonin (four grains) was given to Li-Kha (I.) at ten a.m. on 

 the 29th, and the same dose at seven p.m. No effect apparent. 



Turpentine Spray inhaled by Li-Kha (I.) at ten a.m. August 1st. 

 No result. 



Quassia Tincture Spray inhaled for eleven minutes at mid-day 

 August 1st by Tiong-Seng (II.). No result. 



Besides these I have tried one or two experiments with electricity, 

 but they proved barren and need not be detailed. 



Referring again to your Quekett Club communication of 27th 

 February, I would ask you if Dr. Bancroft has published his obser- 

 vations on the dog louse as intermediary host of Filaria immitis ? 

 Unless he has observed metamorphosis of the embryo in the louse's 

 stomach it is premature to conclude that this is the intermediary 

 liost. Did the louse play the role he assigns to it ? then we might 

 expect to find Filaria immitis in the dog in all countries wiiere the 

 louse is found. The intermediary host is, I fancy, the principal 

 element in determining the geographical spread of such parasites. 

 A little reflection soon convinces one of this. 



Before concluding this letter I would suggest that Dr. Somer- 

 ville's statements about the habits of the Chinese, with regard to 

 the use of drinking water, should not be received until he, or some- 

 one else, has given us the details of the investigations that have led 

 him to the conclusion that the Chinese do not drink uncooked water. 

 1 have been many years in China and mix a good deal with tlie 

 people, and the outcome of my experience is that, like other people. 



