FOURTEENTH WEEK. 



The work of this week is elective. For directions see under 

 twelfth week. 



ELECTIVE WORK. Morphology. 



If this subject is elected the whole of one of the following groups 

 must be done: 



GROUP I. Venation of grasshopper wings. Needed: Slides, 

 large covers, alcohol, oil of cloves, Canada balsam, a number of 

 grasshoppers. 



Mount all the wings of at least twelve grasshoppers in balsam, as 

 directed under field work, being very careful to note on each slide the 

 source of each wing, also mount and label the specimens from which the 

 wings were taken. 



THIRTEENTH WEEK. Make careful drawings of the front and 

 hind wings, showing the principal veins in the two most different 

 species. 



FOURTEENTH WEEK. Compare the two sides of each insect and 

 describe the amount and nature of the differences. 



FIFTEENTH WEEK. Compare the wings of different specimens 

 of the same species, describing the amount and nature of the differences. 

 How do these variations compare with those found in the two sides of 

 the same specimen ? 



SIXTEENTH WEKK. Compare the wings of different species, 

 describing the amount and nature of the differences. How do these 

 compare with those within the species ? 



GROUP II. The tongue of the house fly. Needed: Test tube or 

 beaker, a number of vials, needles in handles, camel' s-hair pencil, 

 alcohol, borax carmine solution, acid alcohol, oil of cloves, Canada 

 balsam, slides, covers, paraffin bath, label, plate of glass, microtome, 

 Schallibaum's fixative, microscope, and a number of house flies. 



TWELFTH WEEK. Heat water to boiling, and after removing 

 from the fire, drop into it the freshly -removed heads of a number of flies. 

 After three minutes remove the tongues from the head, leaving the 

 former a half an hour in 50% alcohol. They are then placed in strong 

 alcohol for one hour and then left over night in borax carmine. In the 

 morning they are washed in acid alcohol and then placed in strong 

 alcohol till next week. Treat some others in hot water and then remove 

 and mount the tongues in balsam, as directed under field work. 



