AUTHOR S ABSTRACT IP THIS PAPER ISSUED 

 BY THE BIBLIOOEAPE SERVICE OCTOBER 20. 



THE EFFECT OF TEMPERATURE ON CROSSINGOVER 

 IN DROSOPHILA 



HAROLD H. PLOUGH 



Zoological Laboratory, Columbia University 



NINE FIGURES 



CONTENTS 



I. Introduction 148 



The chromosome theory of linkage 148 



Variation in linkage intensity 148 



II. Mutant stocks and methods 150 



III. Negative results 152 



Moisture 152 



Starvation 153 



Increased fermentation of food 153 



Iron salts 154 



IV. The effect of temperature 154 



Preliminary experiments 154 



Increase in crossingover after heat and cold 154 



Heat effect apparent for short regions only 157 



Complete anal ysis of temperature effect 158 



Discussion of temperature curve 162 



Failure of heat to cause crossingover increase in presence of little 



crossover modifier 164 



V. The extent of the temperature effect 166 



Increase in percentage of crossingover not inherited 166 



Second brood data 167 



Fractionation of brood counts 170 



Analysis of temperature effect by counts at short intervals 172 



Interpretation of tube data 177 



Control curve of age 177 



Heat effect at one stage in ovary only 180 



VI. Localization of probable point of crossingover in ovaries 182 



Genetic data 182 



Cytological data 186 



Corroborative evidence 187 



Exceptional tube counts 187 



Ineffectiveness of exposure of early larvae 188 



Discussion of data 189 



Synaptic stage probable point of crossingover 189 



Disproof of reduplication hypothesis 189 



147 



a 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 24, NO. 2 

 NOVEMBER, 1917 



