120 INVERTEBRATE ZOOLOGY. 



proventriculns give any indication of teeth as seen in the cricket ? Can yoii 

 find the inner openings for the gastric diverticula ? For the niinary tubules "? 

 What else do you find at the beginning of the intestine ? 



94. Female reproduetive system. Select for this a large female specimen 

 [87] and prepare as for digestive system. The large yellow masses lying dor- 

 sal to the intestine are the ovarial tubules, or organs for the formation of the 

 eggs. Part these in the middle and float them out at the sides of the body, 

 without cutting the tube with which they are connected. The mass will re- 

 solve itself under the lens into a collection of tapering tubules inserted by 

 their larger end into a large tube, the oviduct. How many separate ovarial 

 tubules compose one of the lateral masses ? What is the condition of the 

 upper, free end of the oviduct ? Trace the two oviducts down iintil you find 

 thein uniting into one. What relation does this median tube sustain to the 

 alimentary canal V Trace it out to the external orifice and locate it. What 

 relation does it sustain to the rhabdites V The lower portion of the alimentarj' 

 canal may be removed if in the way. Look near the union of the two ovi- 

 ducts, and find a little pyriform sac, connected by a long duct with the exterior. 

 How is this connection made ? The sac is the Receptaculuin seminis, which 

 becomes filled during pairing with male germ-cells (spermatozoa), which may 

 then fertilize the separate eggs as they come down into the median tube. 

 Draw the entire system, putting in enough of the other parts to show relation- 

 ship. Cut off a separate tubule, remove the large egg at the end, and place 

 in the center of a clean slide. Put on a drop of the liquid iised in dissection , 

 and lay on a cover-glass. If there are air l)ubbles, add more of the licpiid, 

 drop by drop, until the cover-glass is full. If there is too much liquid, the 

 cover-glass will float and the excess of liquid must be withdrawn by applying 

 a cloth or bit of blotting paper. Such a preparation is termed a temporary 

 mount. Examine this with the compound microscope 60-80''. [As this instru- 

 ment is first introduced in this place, its use must be explained.] Of what 

 does the tubule consist ? What idea do you gain concerning the formation of 

 eggs ? Draw the specimen. [Stained preparations and sections will give 

 further information on this subject and will be studied later.] 



95. Male reproduetive system. This consists, like the female system, of a 

 system of txibules which secrete the germ cells, connected with excurrent 

 ducts. Prepare a male specimen as above, and examine the orange yellow 

 mass lying in the abdomen above the intestine. This is the testis, and may 

 be resolved into a doiible bundle of nearly transparent clul)-shaped sacs, sur- 

 rounded by a lace-work of yellow fat. The two bundles of spermaiic tubules 



