216 
Sensory Perceptions in TicTis 
organ. It seems doubtful whether ticks po.ssess any gustatory organs 
as in our experiments the ticks fed on both normal salt solution 
and liquid gelatin, substances which could not present the slightest 
resemblance to blood as regards taste. 
Summary. 
1. All stages of Argas persicus are negatively phototropic. In 
addition, they are also susceptible to pronounced differences in the 
intensity of the illumination and select the darker places. 
2. In the gorged state, the ticks are slightly positively geotropic. 
In the unfed state, this property is not developed. 
3. At all stages the tick endeavours to bring a,s much of its 
surface as possible in contact with its surroundings. 
4. A. persicus is attracted by heat. 
5. In all stages an olfactory sense is well developed. 
6. “ Haller’s organ ” is olfactory in function and constitutes a 
means by which a tick is able to recognise its host. By depriving ticks 
of this organ it is possible by sidtable means to cause them to feed on 
media other than blood, thus showing that a sense of taste is absent. 
Argas jicrsicxis, Ornithodorus moubata and Hyalomma aegyptium have all 
given similar results with regard to the latter point and we believe that 
this constitutes a method by which perhaps other blood-sucking arthro¬ 
pods, after being deprived of the oi'gan or organs necessary for the 
recognition of their hosts, may be made to feed on any desired medium. 
REFERENCES. 
Batelli, a. (1891). Note anatomo-fisiologiche sugli Ixodini. Communicazione 
Preventiva, Part 11. Monitore Zoologico Italiano, ii. 
Haller, G. (1881). Vorlaufige Bemerkungeii liber das Gehororgan der Ixodiden. 
Zool. Anz. IV. 165-166. 
Lahille, F. (1905). Contributions k I’etude des Ixodides de la Republique 
Argentine. Anales del Minist. de Agric. Seccion de Zootecnia etc., ii. 107-109. 
(Buenos Aires). 
Ndttall, G. H. F., Cooper, W. F. and Robinson, L. E. (1908). On the Structure 
of “ HalleFs Organ ” in the Ixodoidea. Parasitology, i. 238-242. 
