4J AN JNTR01 \TOMOLOGY. 



alternate contraction and recovery of the figure of the abdomen in 



:ical and tra: 



T/L :s. In insects the male and female repro- 



ductive organs a d in different individuals. In many in- 



there are marked external sexual differences of size, form, coloring, 

 or character of appendages. In others it is difficult to determine 

 the sex without dissection. The reproductive organs vary greatly in 

 form, but agree in certain general characteristics. They are k 

 taincd in the abdomen, are paired, and usually open by a common 

 duct near the caudal end of the body. (In the May-flies and I 



productive organs of each side have a distinct opening.) 



In the female there is in the abdominal cavity on each side an 



a compound organ consisting of a series of parallel 



tubes opening into a common rii-idnct. Sometimes these tubes are 



attached to each other so as to form a compact body ; in other >pe- 



ii tube is free for a greater or less part of its length. '11 

 tub< .pering in outline, the larger end being joined to the ovi- 



duct. Within these tubes, even in the larval state, may be found 

 the developing eggs, each tube containing a single row of them grad- 

 ually increasing in si/.e from the small end of the tube towards its 

 opening into the oviduct. The oviducts of the two sides unite a short 

 from the external opening and form the ra^'ina. There are 

 usually accessory glands opening into the vagina, whose secretions 

 serve to surround the eggs or to fasten them to the objects upon 

 which they are laid. Connected also with the vagina arc- one or 

 more pouches, the rcccptdcitla sciiiinis, within which the reproduc- 

 fluid of the mal< ived and stored. This fluid retains its 



fertilizing properties for a long time. Thus the <|iieen-bee or ant 

 pairs but once, though she may continue to lay fertile eggs for ye 



fertilization of the eggs of ins, .it the time- they 



are laid. There is in one end of the shell of the egg one or more- 

 pores known as mlcropylcs. Through these the >permatozoa enter 

 the egg. as it passes the opening of the receptacula seminis. 



In ^ome cases, at least, it is not necessary that an egg should be 

 <1 in order that the embryo should develop. This has been 

 proven with the Honey-bee. But so far a vn the unfertil- 



ized eggs of the bee produce only m 



The organs of the male consist of a number of tubular glands, 

 often coiled together so as to form an apparently compact body, 

 the tistcs. These like the ova paired and located in the 



abdominal cavity. The efferent ducts of these glands, the vdsa <i 



