1903-1904-] Report of the Microscopical Section. 145 



whole length of the body. The foUowings parts may be 

 distinguished : — 



(a) The hxiccal sac, a thin-walled sac lying within the first 

 two or three segments. 



(6) The pharynx, a spacious thick-walled structure extending 

 back to the sixth segment. 



(c) The oesophagus, a tube continued back to the fifteenth 

 segment. 



{d) The crop, a large thin-walled sac lying within segments 

 fifteen and sixteen. 



(e) The gizzard, a whitish thick-walled sac in which the 

 food is crushed. 



(/) The stomach proper, surrounded by large yellow cells. 



{g) The intestine. 



The segmental organs, or nephridia, are delicate tubes opening 

 externally upon the ventral side. They are excretory organs. 



The earthworm is hermaphrodite, but not self-impregnating. 



There are no special ganglia but simply swellings of the 

 nerve-cord. At the anterior end of the nerve-cord there are 

 two outgrowths — one on each side — at the end of each of 

 which is a small jelly-like sphere inclosing a small particle of 

 lime. These are called otocysts, and are regarded as elementary 

 ears. 



Along with the earthworm were considered the morphology 

 and life-history of several Parasitic Worms, such as the Tape 

 Worm {Tcenia solium) ; the Fluke (jDistoma hepaticum), the 

 cause of the fatal disease in sheep known as the " rot " ; and a 

 singular nematoid worm called Trichina spiralis. 



The Crayfish (Astactis fluviatilis) was chosen as the type of 

 the Crustacea. Its external and internal morphology were 

 fully described and the functions of the various organs ex- 

 plained. 



Lisect Morphology. — The principal characteristics of Insects 

 were described as being — Exoskeleton composed of chitin ; 

 respiration by means of tracheae; body with distinct head, 

 thorax, and abdomen ; head with compound eyes, and one 

 pair of antennary organs ; thorax bearing three pairs of legs 

 and usually two pairs of wings ; and abdomen limbless. The 

 type studied was the Cockroach (Blatta orientalis). 



On the head is one pair of long jointed antennae and one 



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