CONTENTS. 



Page. 



PREFACE 3 



INTRODUCTION 5 



DEVELOPMENT OF THE PERITHECIUM 



The mycelium and the origin of oogonium and antheridium 8 



Fertilization 10 



Degeneration of antheridial wall and cytoplasm 12 



Development of the ascogonium and origin of the asci as binucleated cells. . . 15 



Secondary mycelium, appendages, and penicillate cells 21 



Function of appendages and period of spore formation 24 



MORPHOLOGY OF THE ASCOCARP 



Review of recent work on the development of various Ascomycetes 29 



Dangeard's conception of the gametophore 28 



Conclusions as to morphology of ascocarp and asci 29 



SPECIAL NUCLEAR PHENOMENA 



Relative size of nuclei and cells in the ascocarp 30 



Structure of nuclei and relations of central body and chromatin in gametes 



and ascogenous cells 31 



Nuclear fusion in ascus 36 



Synapsis, spirem, number of chromatin filaments 39 



Spindle formation, equatorial plate, and anaphases 43 



Formation of the daughter nuclei 46 



Second and third divisions 47 



Development of ascospores by free cell-formation 48 



Summary of relation of central body and chromosomes in the development 



of the ascocarp 52 



THEORETICAL DISCUSSION : 



THE CENTRAL BODY IN PHYLLACTINIA 



Polar organization of the nucleus 53 



Central body a permanent structure 54 



PERMANENCE OF THE CHROMOSOMES 



The organization of the chromatin in resting nuclei and segregation of the 



chromosomes 56 



Individuality of chromosomes 57 



Review of data as to connection of chromosomes and centrosome 59 



THE NUCLEAR FUSION IN THE ASCUS 



Comparison with fusion in oogonium and in ascidium of rusts 61 



Doctrine of the nucleo-cytoplasmic relation 64 



Relation of assimilation and growth to cell and nuclear division 67 



Conclusions as to origin and nature of fusion in ascus 71 



Effects of development of conjugate nuclear division 72 



