collected from Cow 455 on the 14th June, were exposerl to a température of 
o° C for ^ hour daily from the 28 th June to içth July 1907. 
Twelve days later — gist July — they hatehed. 
(a) Ox 47/. Infested on the 2^rd September with four of these adult Rh. 
appendiculatus (53 days old). Piroplasma parvum appeared from the 23rd to 
33rd days, on which latter date the beast died. 
Post mortem Examination revealed ail the typical lésions of East Coast 
Fever. 
(b) Calf 441. Infested on the 22nd October 1907 with eight Rh. appendi- 
culatus adults of the same brood which had been exposed to a température 
of o°.C for \ hour daily from the 28th June to 1 pth July (At the date of infes¬ 
tation these adults were 95 days old). 
Piroplasma parvum appeared from the ioth to ipth days, and the beast 
died on the 11 th November. 
Post mortem examination revealed ail the typical lésions of East Coast 
Fever. 
Conclusions. — T. Engorgée! nymphae of Rh. appendiculatus 
when exposed to a température of o° C. do not hatch as quickly 
as under normal conditions. 
Of the engorged nymphae collected on the iqth June, those 
exposed to a température of o° C. for -J hour dailv from the 28th 
June to igth July, 21 days, hatehed on the 3ist July, or 46 days 
after collection, whilst those kept in the ordinary Pétri dishes 
at a normal température, hatehed on the i6th July, or 32 days 
after collection. 
II. Engorged nymphae of Rh. appendiculatus, collected from 
a beast suffering from East Coast Fever, and exposed to a tem¬ 
pérature of o° C. for J hour daily for 21 days, were capable de 
transmitting Piroplasma parvum as adults; in one case these 
adults were 53 days old, and in the other 95 days old. 
Expf.riment N° 4. — With larvae of Rhipicephalus decoloratus (the blue 
tick). 
(a) Larval ticks exposed to a température of -i8°C. 
Date 
Time kept this température. 
Resuit 
July 3,07 
15 minutes 
none died. 
July 3,07 
25 minutes 
majority died. 
July 3,07 
30 minutes 
ail died. 
July 2,07 
60 minutes 
ail died. 
(h) Larval ticks of 
Rh. decoloratus, exposed to 
a température of -5°.C. 
Date 
Time kept this température. 
Resuit 
July 5,08 
5 hours. 
none died. 
July 10,08 
10 hours 
none died. 
July t1,08 
24 hours. 
none died. 
July 12,08 
48 hours. 
majority died. 
