RESULTS OF CROSSING TWO HEMIPTEROUS SPECIES. 199 



It may be said that in every paper representing cytological 

 research one or more hypotheses are on trial and it is certainly 

 the privilege of the investigator to select for illustration such 

 evidence in his preparations as support his own convictions in 

 regard to the hypotheses under consideration. 



Our skepticism of the sex-determination theory led us to 

 study our preparations of Anasa tristis with 1 a view to deter- 

 mining whether the phenomena involved in the theory were 

 sufficiently constant to justify it. We found enough evidence 

 to fully confirm our skepticism and we claim that we had the 

 right to select that evidence from our preparations and give it, 

 with as much emphasis as possible. 



The facts are simple and clear. We demonstrated that in 

 Anasa tristis the reverse of the facts demanded by the sex- 

 determination theory were clearly present and could be illustrated 

 by photographs. The interesting feature in these opposing 

 observations is the fact that we do not deny the observations of 

 our opponents, whereas their belief in the causal nature of the 

 chromosomes compels them to set our observations aside or to 

 resort to strained explanations in order to account for them. 



It is the old story so familiar to cytologists if a feature is 

 where, hypothetically, it ought not to be, it is an artifact, and if 

 it is not where it ought to be, it is due to faulty technique. 



We believe that the photographs of our preparations prove 

 conclusively that the accessory chromosome in Anasa tristis 

 does not always fail to divide in the second spindle and the case 

 may safely rest on a comparison of McClung's photographs of 

 his preparation with ours. 



We claim that the facts we have demonstrated in Anasa tristis 

 are at least worthy to be placed in evidence against the chromo- 

 some theories that necessitate such facts being thrown aside as 

 artifacts or as expressions of a pathological condition. We hold 

 that they have at least the same value as normal variations in 

 other organs of the cell and that they should be accepted as the 

 same type of evidence we gave in '05 against the theories based 

 on definite forms of the chromosomes. We demonstrated a 

 degree of inconstancy in the form of the chromosomes of Allolobo- 

 phora foetida that should not exist if the hypotheses were valid. 



