343 



(d) The salivary glands. A number of small 

 tubules near the rostrum on either side. 



(e) The ovary. A brownish elongated organ 

 (o). Examine with a lens and note the large ova. 



(/) The malpighian tubules ? (t). 



5. To cut sections. Snip off portions of the 

 chitin before placing in alcohol. Do not over- 

 harden. Use a sharp razor. Fix the sections to 

 the slide by the hot water method. Stain with 

 haeraatein. Observe the following tissues : — 



(a) An external chitinous layer and a single 

 row of columnar cells forming the cuticle. 



(6) The alimentary canal and its appendages 

 cut in various planes. 



In the diverticula, distended with blood, the 

 epithelium is flattened ; in the empty diverticula 

 the epithelium is columnar, and the cells often 

 have processes projecting into the lumen. Note 

 the peculiar crystalline contents of the diverticula 

 (altered blood). 



(c) Large cells with large nuclei (ova). These 

 are arranged around branches of the follicular tubes 

 as in the mosquito. 



{d) Undeveloped follicular tubes containing 

 large cells. 



(e) Tissue, rich in nuclei, especially in the 

 posterior portion of the body (= Fat body of 

 insects). 



(/) A large nerve ganglion anteriorly. 



(g) Muscle fibres passing chiefly ventrad and 

 dorsad, tracheae supplying the viscera. 



Classification of Ticks 



Ticks are divided into two families — 



1. Argasidae, scutum absent. 



2. Ixodidae, scutum present. 



