Biology of I. ricinus 311 



when Gene's organ was not pricked but simply made to retract itself by 

 being touched with a small rod. The eggs which then appeared had dried 

 up in 6-8 hours, whilst eggs laid normally remained fresh for weeks 1 . 

 Wheler (1899, p. 110, Fig. 20, republished 1906, PI. V, Fig. 3, here 

 reproduced — see Figs. 284-287) has described and also figured oviposition 

 in ricinus. He notes that in unfed or partly fed females the capitulum 

 protrudes forward but that in fully gorged females it is depressed. It 

 may, in fact, point slightly backward, especially when they are ovipositing. 

 Wheler's description agrees with those of Gene" and Bertkau which were 

 unknown to him. The female he observed took three minutes to lay an 

 egg, after which there occurred a rest of six minutes before the process 

 was repeated. Samson (1909, pp. 221-223, Fig. 14) also describes the 

 process in the same manner as Gene. She states that the egg is turned 

 to and fro for about two minutes by Genu's organ, and she describes 

 the internal glandular structures which are connected with the latter. 



Regarding the duration of oviposition and the number of eggs laid by 

 Ixodes ricinus, we glean the following notes on the subject from the 

 literature : 



Gene" (1844, p. 775) states that oviposition lasts 10-30 days, during 

 which time a female may lay 1000 to 3000 eggs. Oviposition ceases 

 when the female is disturbed. 



Bertkau (1881, p. 147) observed a gorged £ , which dropped of her 

 own accord from a hedgehog on May 28th ; by June 9th she had laid 211 

 eggs. She then continued laying until June 20tli, when she was killed, 

 having laid 847 eggs. 



Wheler (xn. 1899) observed a £, collected on April loth, which 

 began to oviposit on May 12th (interval of 27 days). As in other ticks 

 we have observed, the $ 's body at this time showed yellowish streaks 

 (due to the increased excrement contained in its malpighian glands). 

 This ? laid 2050 eggs. 



Kossel, Schlitz, Weber and Miessner (1903, p. 40) state that oviposi- 

 tion commences 8 days after the replete fertilized female has dropped from 

 the host, and that it lasts 8-14 days, during which period 100 to 1000 

 or more eggs may be laid. 



Galli-Valerio (1908, p. 611, with figure) illustrates, by means of a 



1 Schleohtendal (1891, p. 11) givea a very imperfect description of oviposition observed 

 in the case of a female of undetermined species, belonging apparently to the Ixodidae, 

 which was received in a consignment of fossils from Persia. He observed the protrusion 

 and retraction of Gene's organ and thought it might be a glandular structure. 



