1912] YAMANOUCHI—CUTLERIA 497 



Figs. 88, 88#. — Portion of a female gametangium of 18 cells: one nucleus 

 in anaphase, which is shown under higher magnification in fig. 88a. 



Fig. 89. — Cross-section of mature female gametangium in 4 tiers. 



Fig. 90. — Cross-section of mature female gametangium in 8 tiers. 



Fig. 91. — Two cells of a mature female gametangium: the plastids and 

 dense cytoplasm are thick along the inner wall; nuclei in resting condition. 



Fig. 92. — One cell of a mature female gametangium: plastids and cyto- 

 plasm are thick toward the outer wall; nucleus in resting condition. 



Fig. 93. — A female gametangium entirely emptied after the escape of 

 female gametes. 



PLATE xxix 



The union of gametes and germination of the fertilized female gamete 



Fig. 94. — Two male gametes which have stopped the swimming movement; 

 cilia are withdrawn, nuclear membranes are scarcely visible, and the reticulum 

 shows 24 chromosomes. 



Fig. 95. — Union of male and female gametes: nucleus of the male gamete 

 shows 24 chromosomes and that of the female gamete is in the resting condition; 

 no cell membrane is recognizable around the gametes. 



Fig. 96. — Cytoplasm of male gamete is entirely fused with that of female 

 gamete and the whole body of the united gametes has about assumed the 

 spherical form; cell membrane has appeared; male nucleus still shows 24 

 chromosomes. 



Fig. 97. — Male nucleus has advanced toward the female nucleus. 



Fig. 98. — Male nucleus has moved nearer toward the female nucleus. 



Fig. 99. — Male nucleus is attached to the female nucleus. 



Fig. 100. — Male nucleus, showing 24 chromosomes, and female nucleus in 

 resting condition. 



Fig. ioi. — Male nucleus very closely applied to the female nucleus; 24 

 chromosomes of the male nucleus still recognizable; a part of the cell wall of 

 the sporeling has thickened. 



Fig. 102. — Part of the male nucleus, evidently consisting exclusively of 

 chromosomes, has become submerged in the female nucleus, which is in the 

 resting condition. 



Fig. 103. — Male nucleus has completely entered into the female nucleus; 

 dense chromatin granules are to be seen at the part of female nucleus w r here 

 the male nucleus has entered. 



Fig. 104. — Fusion nucleus: network contains a number of chromatin 

 granules that show no distinction between those derived from the male and 

 female nuclei. 



Fig. 105. — Fusion nucleus is in the resting condition. 



Fig. 106. — Prophase: 48 chromosomes and a nucleolus are present ; the 

 chromosomes are apparently alike both in form and size; the sporeling shows 

 an elongation at a point where the cell wall is thickened. 



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