8 INHERITANCE IN SILKWORMS, I 



Characteristics of shape. 



Several, as constricted, broad-ended, tapering, etc. (see PI. IV), 

 but not used in the present studies. 



Adult characters. 



Patterning of the wings (see PI. II), venation of the wings, dark- 

 ness of wings and body, etc., but no character found to be distinctive 

 of a race. 



In addition to these differences still other racial ones occur in 

 connection with properties of the silk, but with these I have nothing to 

 do in this paper, as they have not been used by us in the inheritance 

 studies. 



Other characters not racial but occurring as individual variations 

 have been noted and some have been made use of to some extent in 

 the studies. For example, melanism of the moths (darky moths) 

 and the degree of patterning of the wings, variations in the wing- 

 venation of the moths, various teratologic sports, the phenomenon of 

 double and triple cocooning, the flight capacity of the moths, etc., have 

 all been subjects of more or less observation and experiment. 



As the characteristics used will be described in more detail in con- 

 nection with the particular accounts of studies in which they are used, 

 this general statement of the variety of characters available to the 

 student of silkworm variation and heredity may suffice. It should be 

 stated at once, however, that among these various silkworm character- 

 istics or variations some are distinctly alternative or discontinuous 

 in character while others are continuous or fluctuating in variational 

 character. Thus in this one species of animal, opportunity is well 

 afforded for studies of the behavior in inheritance of both types of 

 variations. 



