CONTENTS. 



PAGE. 



Part I. Introductory S 



/ Mendel's law of segregation ^ 5 



jLinkage and chromosomes S 



^rossing-over 7 



'The Y chromosome and non-disjunction 8 



Mutation in Drosophila ampelophila lO 



Multiple allelomorphs 1 1 



Sex-linked lethals and the sex ratio 14 



Influence of the environment on the realization of two sex-linked characters 16 



Sexual polymorphism 17 



Fertility and sterility in the mutants 18 



Balanced inviability 



How the factors are located in the chromosomes 



The sex-linked factors of Drosophila 



Map of chromosome X 



Nomenclature 



Part II. New d.'vta 



White 



Rudimentary 



Miniature 



—Vermilion 



^Yellow 



Abnormal abdomen 



Eosin 



Bifid 



Linkage of bifid with yellow, with white, and with vermilion 



Linkage of cherry, bifid, and vermilion 



Reduplicated legs 



Lethal 1 



Lethal \a 



Spot 



Sable 



Linkage of yellow and sable 



Linkage of cherry and sable 



Linkage of eosin, vermilion, and sable 



Linkage of miniature and sable 



Linkage of vermilion, sable, and bar 



Dot 



Linkage of vermilion and dot 



Bow 



Bow by arc 



Lemon body-color ., 



Linkage of cherry, lemon, and vermilion 



Lethal 2 



Cherry 



A system of quadruple allelomorphs 



Linkage of cherry and vermilion 



Compounds of cherry 



Fused 



Linkage of eosin and fused 



Linkage of vermilion, bar, and fused 



3 



y 



19 



22i 

 24 

 25 



25 



26 



27 



27 

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 29 

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 31 

 31 

 32 



33 

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 37 

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 46 



47 

 48 



48 



49 

 SI 

 SI 

 51 



52 

 S3 

 54 

 S6 



