Analysis of Heteeogbneitt in Some Simplest Chaeactees 307 



extremes as represented in figure 38, a and &. It may extend medianward 

 towards i, but this is always accompanied by a lateralward movement from & 

 towards c. These two always move toward each other at the same time, produc- 

 ing a mutual movement to unite. Likewise c and e ant. may simultaneously 

 move towards each other and unite. The movements of c and h towards each 

 other, of e and /, and the movements of c and e ant. are shown in figure 35. 

 These states are inheritable in pure homozygous biotypic lines and are alterna- 

 tive to their absence in crosses. No other variations in direction are known in 

 spot c in L. signaticollis, either in nature or in cultures, and none has thus far 

 been induced by experimental means. 



The biometric study of this area shows little of interest. In figure 26 are 

 given the statistical determinations for the populations in restricted colonies at 



Fig. 26. — Biometric treatment of the left spot c in 

 L. signaticollis at Cuernavaca and at Atlixco. 



Atlixco, in the S'tate of Puebla, and Cuernavaca, in the State of Morelos, 

 Mexico. In the Cuernavaca colony determinations of left c spots were made in 

 1904, 1905, and 1906, and show a mode and a wide range, but the spot is never 

 absent. In the Atlixco population for the same time is shown a lower mode. 

 Both modes are higher than the modes for this character in L. undedmlineata, 

 and the mode for Cuernavaca is the highest known and occurs only in one 

 restricted area. Other colonies in the Cuernavaca Valley have much lower 



modes. 



Biometric observations upon the state of the population at these colonies in 

 the Cuernavaca area were made in 1904 to 1908, a total of ten observed gener- 

 ations. The three colonies were different in conditions, especially in the water- 

 relation. The Bosoco colony was located in the shallow, steep-sided barranca 

 (50 to 100 feet deep) to the east of the town, and so located that the deep, rich 

 soil was moist, due to drainage conditions. The Quauhtemotzin colony was on 



