524 



GENERAL BIOLOGY 



grafting (budding) is available for late summer, where 

 mature buds are selected for immediate transplantation. 

 Cone galls needed for study 42, abound on the tips of the 



twigs of our common 

 glaucous willows, 

 along streams and in 

 sunny wet places 

 generally. The gall 

 midge larvae spend 

 the winter in the galls, 

 fully grown, and 

 transform in early 

 spring. If brought 

 into the laboratory 

 any time after Christ- 

 mas (or after heavy 

 freezing has occurred) 

 they will enter the 

 pupa stage in a few 

 weeks or less and 

 adults will appear two 

 weeks thereafter. In- 

 dividual lots collected 

 by students may by 

 them be tied up in 

 squares of cheese- 

 cloth, and the midges 

 will develop normally 



Fig. 285. Diagrams of the leg structures of diving beetles. ^, the hind leg of 

 Laccophilus. r, trochanter. 5, femur, t, tibia, x, the overlapping lobe or brace 

 of the femur that limits and guides the action of the tibia 1, 2, 3, 4, 5, the seg- 

 ments of the tarsus, e, the single claw c, c, c, c, c, c, c, jumping spines, v, v, 

 swimming fringes, z, tibial spurs. 



b, two segments from the middle of the tarsus, showing at n the little transverse 

 group of apical bristles characteristic of Acilius and its allies. 



c, the knee joint, showing at m the linear group of setae that is characteristic of 

 Agabus and its allies. /, femur, t, tibia. 



