610 MINNESOTA BOTANICAL STUDIES. 



hyaline portion, in many cases, at least, there are visible darker 

 and lighter areas. 



A group of basal cells was observed from which were given 

 off directly reproductive cells. Three of these filaments con- 

 tained the swollen cells. In the fourth filament which contained 

 three cells, the twelve spores were just ready to escape. The 

 cell- walls enclosing them were very faintly visible, as a mere 

 outline. The spores as observed were in active movement, slid- 

 ing upon each other with a quick, jerky motion like that of the 

 bell animalcule as it withdraws itself upon contact with any 

 object. They moved in a direction at right angles to the fila- 

 ment. Two lying side by side moved in opposite directions at 

 the same time. The spores of the middle cell broke their way 

 out first, those of the first and third cells following. For 

 some time after their escape they kept up the jerky movements 

 backwards and forwards, after which they suddenly started off 

 in different directions across the field. The slide was then made 

 into a permanent mount. 



Four zoospores each of which had a very delicate wall be- 

 tween it and its neighbors, were observed to escape from a cell. 



A large number of megazoospores were measured and the 

 limits of diameter were found to be 6.5 and 7.5 mic. 



While the spores were most vigorously active, from 9 

 o'clock to 12 o'clock A. M., some slides containing them were 

 stained for the- purpose of recognizing the cilia. The direc- 

 tions given by Zimmermann (I) for staining the cilia of algae 

 were followed, with the exception that the carbol fuchsin was 

 allowed to act only three minutes instead of fifteen. Perman- 

 ent mounts were thus prepared and in this manner the spores 

 corresponding in size- Hb those of the cells just described were 

 seen to have four cilia (PI. XXXII, fig. 17). 



On the tenth day while material in a drop culture was under- 

 going examination, gonidangia occup3ang the upper portions 

 of filaments, were seen to contain what appeared to be germin- 

 ating spores (PI. XXXII, fig 18). The tubes did not arise 

 from successive spores, but every other one, perhaps, was in 

 this condition. It was noticed that all the germinating fila- 

 ments from a single branch projected in the same direction and 

 at right angles to the branch. Subsequently it appeared, in a 

 group of sporiferous branches lying together, that all the ger- 

 minating filaments extended in the same direction. However, 

 exceptions to this rule occur. 



