Butters: OBSERVATIONS ON RHODYMENIA. 207 



projects on one side of the thallus and possesses a fairly thick 

 fruit wall of five or six cells in thickness arranged irregularly 

 inwards. At the bottom of the fruit cavity is to be found the 

 placenta formed of numerous small cells closely packed to- 

 gether and lying on the medullary layer of large cells. 



" From the placenta the gonimoblast of more or less irregular 

 shape, is borne on an elongated style cell and spreads upward 

 into the empty fruit cavity. 



"This gonimoblast is composed of numerous pear-shaped 

 lobes which lie close together. The spores of these lobes be- 

 come ripe nearly at the same time. 



" The ostiole is generally quite in the center of the projecting 

 fruit wall, and is similar to the ostioles of the kindred species." 



Collection and Preservation. All the material at hand was 

 collected by Miss Josephine E. Tilden at Port Orchard, Kitsap 

 County, Washington, on August 2, 1897. The specimens were 

 dredged in water 4-6 fathoms deep. A small portion of the 

 material was killed and preserved in 80 per cent, alcohol. The 

 larger part of the material was dried. By soaking, this dried 

 material so far regained its original form that the anatomy could 

 be well studied although the cell contents were largely disor- 

 ganized. All the observations upon the stipe and the prolifera- 

 tions were made upon this dried material ; observations upon 

 other points were- made mainly upon the alcoholic material. 



Methods. The dried material was soaked in water until it 

 regained its natural consistency. Various methods were em- 

 ployed in cutting the tissues. Much of the material was cut 

 upon the Osterhout freezing chamber. (Osterhout, W. J. V., 

 p. 1950 The alcoholic material was first passed into water 

 preferably through about three intermediate grades of dilute 

 alcohol. When the alcohol was completely removed the mate- 

 rial was in some cases infiltrated with gelatine solution and then 

 mounted in a drop of gum arabic solution upon the freezing 

 chamber ; in other cases it was embedded directly in the gum 

 arabic. On account of the firm nature of most of the tissues, 

 this method of mounting directly in gum arabic proved quite as 

 successful as that in which the tissues were first infiltrated with 

 gelatine. 



The sections, as soon as they were removed from the knife, 

 were passed into 20 per cent, glycerine. Those which were to 

 be stained were transferred from this glycerine to the staining 



