672 MEDICAL ENTOMOLOGY 



which consists for the most part of flattened cells of the membraneous 

 wall of the ovary. Further growth results in the egg being liberated 



into the lumen of the ovary ; it is not very clear how 

 The organs in the thig takeg , but ^ is " probable that t " he neck of 

 impregnated condition . , 



the funicle is forced open. 



The mature egg is globular in shape and of a brown colour ; its 

 cytoplasm is packed with granules, so that the nucleus is not visible. 

 The eggs pass from the oviducts to the uterus and from there into 

 the vagina, from which they are finally expelled in a manner which will be 

 described presently. 



The circular muscle fibres of the oviducts and uterus are much better 

 developed, and the former stand but as thick white cords. The muscle 

 fibres of the vagina also increase enormously and the strands from these 

 pass inwards to the cells lining the lumen. These, instead of being flat 

 as in the unimpregnated condition, are now cylindrical, and as a result 

 the lumen has become narrowed. 



The vaginal glands, which in the unimpregnated condition were 

 undeveloped, now take on their function. The cells lining the lumen 

 are small and columnar in shape and have large nuclei ; clear drops 

 of secretion collect around the nucleus until the cells become almost 

 completely filled with it. This secretion probably aids in the passage 

 of the egg from the first part of the vagina into the vestibule. 



Egg laying begins at a varying period after the female leaves the host. 

 Some time before the eggs are deposited the capitulum is pressed down 



till it comes to lie at right angles to the body and is 

 Oviposition . . . . ? , , . , " 



almost in apposition with the external genital opening. 



Gene's organ is now protruded (Argatini) until it projects over the 

 capitulum ; the vestibule is everted by the action of a complicated 

 musculature and the palps are directed outwards. An egg is now 

 extruded and rolled round until it comes in contact with the sticky 

 secretion of Gene's organ ; when this takes place the organ is withdrawn 

 and the egg is carried on to the dorsal surface of the tick. This explains 

 how eggs which come out of a ventral opening are always found 

 lying over the anterior end of the female. 



The test is of the tick (Plate LXXXVI, fig. 5) is a delicate transparent 



tube, lying in the position occupied by the ovary in the female. Along 



its course there are many cystic swellings, which give it 



The testis an irregular outline. The distal end on each side 



becomes continuous with the vas deferens, there being 



no distinct line of demarcation between them. The greater part of the 



