DESCRIPTION OF PLATES 



Figs. I to 48, 50, 54 and 66 to 71 were drawn from sections with 2 mm. obj. and 12 oc; Figs. 49, 51 

 to 53 and 55 to 65 from aceto-carmine preparations with 2 mm. obj. and 6 oc; Figs. 72 to 77 from aceto- 

 carmine preparations with 2 mm. obj. and 12 oc. The magnification of all of the figures was then 

 doubled with a drawing camera, and the plates reduced one-half. 



Lettering used on Plates 



X = the unpaired, "odd'' or "accessory'' chromosome. 



n = the chromatin nucleolus of the spermatids. 



i = a "supernumerary" chromosome. 



si, S2, S3, Si = I, 2, 3 or 4 supernumerary chromosomes in the same individual. 



Plate I 



Diahrotica vittata 



Fig. I Spermatogonial metaphase, twenty-one chromosomes. 



Fig. 2 First spermatocyte, synizesis stage. 



Fig. 3 First spermatocyte, synapsis stage. 



Fig. 4 First spermatocyte, postsynapsis stage. 



Fig. 5 First spermatocyte, spireme stage. 



Figs. 6 and 7 First spermatocytes, prophase. 



Figs. 8 and 9 First spermatocytes, metaphase. 



Figs. 10 and 1 1 Second spermatocytes, metaphase. 



Figs. 12 to 15 Spermatids. 



Fig. 16 Ripe spermatozoon. 



Diahrotica sorgr. Type I 



Fig. 17 Spermatogonial metaphase, nineteen chromosomes. 



Fig. 18 First spermatocyte, spireme stage. 



Figs. 19 and 20 First spermatocytes, metaphase. 



Fig. 21 First spermatocyte, anaphase. 



Fig. 22 and 23 First spermatocyte, daughter plates. 



Figs. 24 and 25 Second spermatocyte, rest stage. 



Figs. 26 and 27 Second spermatocytes, metaphase. 



