[Annals N. Y. Acad. Sci., Vol. XXXI, pp. 1-30, July 15, 1929] 



CHROMOSOME IRREGULARITIES IN" RELATION TO 

 STERILITY m HEMEROCALLIS FULVA CLON EUROPA* 



A. B. Stout and Torasaburo Susa 



N. Y. Botanical Garden Aomori Agricultural Experiment 



Station, Japan 



CONTENTS 



Page 



Introduction 2 



Chromosome behavior in somatic divisions 3 



The basic or normal number of chromosomes 3 



Irregularities in the number of chromosomes in somatic cells 4 



Chromosome and nuclear behavior during sporogenesis 5 



Synapsis 5 



The normal number of chromosomes in diakinesis 5 



Irregularities in the number of chromatin units in diakinesis and in 



the first meiotic division 6 



Normal stages in sporogenesis 8 



The various types of irregularities 8 



Irregularities in the distribution of chromatin in the first division 9 

 Irregularities in the formation of cell plates in the first meiotic 



division 9 



Irregularities in the distribution of chromatin during the sec- 

 ond division of meiosis 9 



Irregularities in the shape of chromatin masses 10 



The stretching of chromatin material between nuclei 11 



The microspores and macrospores 11 



The number of microspores 11 



Variations in the size of the microspores 12 



The nuclei and the chromosome number in microspores 13 



The viability of the pollen 13 



The abortion of macrospores 13 



Summary and discussion 14 



Summary of the chromosome and nuclear behavior in the Europa clou 14 



The chromosome number for the Europa clon 16 



Increase in the number of chromatin units 18 



Types of sterility involving abortion of spores 20 



The inherent and hereditary nature of spore abortion 24 



The immediate causes of spore abortion 25 



Bibliography 27 



* The publication of this paper has been made possible through a grant from the 

 income of the John James Audubon Fund. 



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