RESEARCH SEMINAR. 243 



three classes: (i) the unicellular sexual organs (gamete-cysts) 

 (2) the multicellular sexual organs (gametangia) and (3) the 

 peculiar multinucleate gametocysts which become sexual cells 

 (ccenogametes). The first class (gametocysts) is found through- 

 out the Thallophytes, and the evolutionary principles governing 

 their differentiation into spermatocysts and oocysts are well 

 understood. The second class (gametangia) is characteristic of 

 the bryophytes and pteridophytes and contains the well-known an- 

 theridium and archegonium of these groups. The possible origin 

 of these structures from the plurilocular sporangium, according 

 to the writer's recently published hypothesis, was discussed. 

 The third class (coenogametes) comprises the remarkable cceno- 

 cytic sexual cells found among the Mucorales, Saprolegniales 

 and Peronosporales. Great interest attaches to their behavior 

 and phylogenetic relations on account of the peculiarities of their 

 structure, which are not found in any other group of organisms. 

 The author's explanation of these conditions was presented in the 

 light of his recent investigations on oogenesis in Vauclicria. 



July 20. The Unorganized Contents of the Plant Cell. By 

 HENRY KRAEMER. 



The micro-chemical and micro-physical properties of the fol- 

 lowing unorganized cell contents were considered : (i) Product 

 of constructive metabolism ; the crystalloidal carbohydrate, starch. 

 (2) Products of reconstructive or destructive metabolism ; A, 

 organic substances --() occurring in the protoplasm and cell- 

 sap, as oils, resins, ferments and proteine crystalloids ; ($) occur- 

 ring in the cell-sap, as crystalline carbohydrates (dextrose, mal- 

 tose, sucrose, etc.) and the crystalloidal carbohydrate inulin ; (<r) 

 occurring in cell-sap or cell-wall, colloidal carbohydrates (gums, 

 mucilages and pectins), tannin, alkaloids, glucosides and calcium 

 oxalate ; B, inorganic substances - - (a] calcium carbonate in 

 cystoliths or in the cell -wall ; (b~] silica in irregular masses or in 

 the cell-wall. 



July 21. The Structure of the Cell-wall. By HENRY 

 KRAEMER. 



The various methods for differentiating the different lamellae 

 of the cell-wall were first considered. The similarity in the 



