28 



converse was the case. The main vector in the region appears to be 

 A. maculipennis [elutus, cf. R.A.E., B, x, 18], and in the Jordan 

 valley, A. superpictus (palestinensis) . Other species found were 

 A.fragilis, A. bifiircatus, and A. ttirkhiidi. 



Zuelzer (M.). Biologische XJntersuchungen an Zecken. [Bio- 

 logical Investigations on Ticks.] — Zeitschr. Iinniunitdtsforschung 

 u. exper. Therapie, Jena, xxx, no. 2, 7th September 1920, 

 pp. 183-201. 



These investigations relate especially to Argas persiciis, A. rcjiexus 

 and Ornithodonis moubata having been used for comparison. 



A. persiciis likes warm and dry surroundings, 26° C. [79° F.l 

 being the optimum temperature, and prefers darkness, hiding in 

 cracks and fissures. It can fast for three or four months, but the 

 statement that it can remain without food for a year is probably 

 incorrect. If opportunity offers, it will suck blood every three 

 or four weeks. After the meal, and only rarely during it, the 

 distended tick secretes a drop of clear coxal fluid (weighing about 

 as much as a fasting tick) ; its normal flat and wrinkled appearance 

 then returns, and it will suck again with renewed energy. A . reflexus 

 behaves similarly, but 0. monhata fairly regularly excretes the fluid 

 while actually feeding. To ascertain what part this fluid may 

 play in the transmission of spirochaetes, nine individuals of 

 0. moubata, harbouring the spirochaete of relapsing fever, were fed on 

 a healthy rat, and the coxal fluid was collected and injected intra- 

 peritoneally into a healthy mouse, producing severe relapsing fever 

 with abundant spirochaetes in the blood. In this case the coxal fluid 

 alone was responsible for the infection. Experiments are being made 

 to ascertain whether only the secretion is infective or whether the 

 actual bite can also be so, as in the case of lice. Other blood-suckers 

 such as Culex, Cimex lecttilarius and Pulex ingest more blood than 

 they require, but in the absence of coxal glands, the undigested matter 

 is excreted with the faeces. 



All important functions in the life of a tick are directly dependent 

 on the ingestion of food. Neither pairing nor oviposition occurs during 

 a period of fasting. After a meal, pairing may occur within from \ to 

 2 hours. The female will pair for two or three days after a meal, and 

 the male for a period up to thirty-two days. Females that had been 

 fertilised after a previous meal oviposited after a new meal without 

 a new pairing being necessary. After pairing, oviposition occurs in 

 from five to fourteen days. The first eggs of a batch are laid singly. 

 Each oviposition lasts three to six days, the number of eggs varying 

 from 30 to 275, according to the amount of food and, perhaps, the 

 date of pairing. A couple, known to be four years old, paired, and the 

 female then laid 50 eggs. Specimens fed on guinea-pigs for years 

 appear normal, but lay a reduced number of eggs. 



The eggs of A. persiciis have an incubation period of 5-6 daj's in 

 summer and 20-25 in winter. The first larval moult occurred after a 

 minimum of 15 days in summer and 28 in winter. After each of the 

 four moults the nymph of A . persiciis must suck blood at once. The 

 total minimum time from the deposition of the eggs to oviposition 

 by the next generation female is nearly six months in winter and about 

 three in summer. 



