HoltZ : OBSERVATIONS ON PELVETIA. 45 



25. Later stage. Shows cavity deepened, filled with mucilaginous 

 remains of cells. 



26. Diagram of the same. 



27. Young conceptacle. Disintegration of cells has ceased. Their 

 mucilaginous remains act as a stopper to the conceptacle. The neck is 

 being formed by new layers of subepidermal cells. Paraphyses are 

 beginning on the wall. 



28. Later stage. Paraphyses and young oogonia have sprung from 

 the cells lining the cavity. Chromatophores abundant near mouth, 

 very few or small in lining cells. Cells in lining of cavity rich in 

 protoplasm. 



29. Nearly mature conceptacle with paraphyses, oogonia and an- 

 theridial branching hairs. Cells in wall of conceptacle have become 

 flattened. 



PLATE XII. 



Anatomical detail. Reproductive organs and paraphyses, x 250. 



30. Beginning of oogone and paraphysis. Oogone cell densely 

 granular. Paraphysis begins as a more slender protuberance of cell 

 in conceptacular wall. 



31. Later stage. Basal cells have been cut off by oogone and 

 paraphysis. 



32. Similar. An oogone anlage preparing to form pedicel cell. 

 Paraphyses elongating and dividing. 



33. Nucleus of young oogone dividing in two. Protoplasm still in 

 communication with that of basal cell. 



34. Later stage, another division of nuclei. The protoplasm of 

 the oogone has been forcibly torn away from that of basal cell, prob- 

 ably in dehydrating process. 



35. Oogone in four- nucleated stage. 



36. Four-nucleated oogone showing thickening of wall and separa- 

 tion of wall into thin exochite and thick gelatinous mesoendochite. 

 The two layers still adhere in places. Wall remains thin at basal 

 pit. 



37. Mature oogone with two eggs. Was mounted in glycerine 

 which caused swelling of walls. 



38. Young conceptacle showing origin of paraphases as protuber- 

 ances from cells lining cavity of conceptacle. 



39. Young branching hairs, showing mode of branching. 



40. Bottom of nearly mature conceptacle, showing oogone, para- 

 physes and branching hairs with antheridia. Antheridial protoplasm 

 is shown in different stages of division, 



41. Single branching hair in glycerine. Antheridia with sperms 

 and swollen walls. 



