RESULTS OF CROSSING. 335 



producing spermatozoa, for the servus inheritance is from the 

 FI female, which must have developed from an egg fertilized by a 

 female-producing spermatozoon of servus. 1 



Thus the evidence that not only the so-called male-producing 

 spermatozoa but also the so-called female-producing spermatozoa 

 can transmit even such an exclusively male character as the 

 intromittent organ, and the fact that these so-called sex-deter- 

 mining spermatozoa do not differ functionally in the transmission 

 of such a character certainly justifies much scepticism as to that 

 sex-determination hypothesis which is based on the assumption 

 of male- and female-producing spermatozoa. 



In the reports of our variolarius by servus experiments we have 

 repeatedly discussed the bearing of the results on the interesting 

 and ingenious hypotheses which attempt to locate Mendelian 

 factors not only in the chromosomes as such, but in definite 

 chromosomes and in definite areas of definite chromosomes, and 

 we have pointed out that the evidence from our results was in 

 direct contradiction to such hypotheses and, further, that the 

 evidence, as stated above, was against the hypothesis that 

 assigned the role of sex-determination to the "sex-chromosomes" 

 of the so-called male- and female-producing spermatozoa. As 

 the evidence bearing on these questions is simply repeated in 

 this variolarius by ictericus cross, we would (to avoid repetition) 

 refer our readers to a recent paper 2 where we have briefly dis- 

 cussed the evidence in relation to these questions. 



We feel almost like apologizing for our persistent criticism of 

 these ingenious chromosome hypotheses so brilliantly launched 

 by Morgan and his pupils 3 and so vigorously advocated by 

 Wilson. 4 



Our scepticism was perhaps primarily due to fourteen years' 

 patient study of the chromosomes of Allolobophora fcetida, these 



1 For the sake of the argument we must assume, for the moment, the existence 

 of male- and female-producing spermatozoa. 



2 Foot and Strobell, Journ. Linn. Soc., London, 1915, pp. 475-486. 



3 A complete list of the literature by Morgan and his pupils is given in their 

 recent volume, "Mechanism of Mendelian Heredity," Morgan, Sturtevant, Muller 

 and Bridges. Henry Holt & Company, 1915. 



4 A forceful presentation and endorsement of these hypotheses was recently 

 given by Wilson in his Croonian Lecture. Proceedings Royal Soc., ser. B, Vol. 

 .LXXXVIII., No. B 603. 



