292 WILLIAM LAWRENCE TOWER. 



the presence of any internal factor, which by its operations would 

 produce this result. Careful examination, however, of the rec- 

 ords which have been kept in the vivarium where these experi- 

 ments were carried on, gave evidence that the differences were 

 possibly due to the conditions surrounding the hybrid series 

 during development. Accordingly, an array of experiments has 





Fig. 3. L. diversa. (A) Adult. Showing the presence on the elytra of lon- 

 gitudinal dark stripes in exactly the same position as the dark stripes in L. unde- 

 cimlineata, and in the position of the absence of stripes in L. signaticollis. (B) 

 Full-grown larva, showing characteristic color pattern. The ground color is bright 

 chrome yellow as in L. signaticollis. (C) Second stage larva, showing character- 

 istic color pattern. The ground color is yellow. 



been carried out to test this point — do the conditions surrounding 

 or incident upon the gametes before and at fertilization and in early 

 ontogeny influence in any way the behavior of characters? As far 

 as this phase of the modifiability of alternative inheritance is 

 concerned, I have essayed to investigate it in two ways: first, 

 by the usual process of hybrid analysis, as it is practiced in all 

 Mendelian work, in which the extracted dominants, recessives and 

 heterozygous forms are isolated and carried on as pure cultures, and 

 again inbred and tested in the usual wa3'5 — essentially experi- 

 ments in analysis to determine germinal constitution; second, I 

 have carried on a series of complicated experiments in synthesis, 

 comparable to those which one would expect to go on in nature when 

 two of these species are brought into contact and hybridized, in order 

 to learn what the result would be if two species should come in contact 

 under different conditions, and hybridize, and these results I shall 

 describe under the head of Experiments in Synthesis. 



