624 MINNESOTA BOTANICAL STUDIES. 



there remained in the shape of the branch evidence of the 

 former cylindrical cell the walls of which had apparently gela- 

 tinized. The cells were green with chlorophyll, in some por- 

 tions colorless, and they contained granules of various sizes. 

 They were 10-12.5 mic. in diameter. 



A detached cluster of branches was observed for several 

 days in a hanging drop culture. It appeared as if all the cells 

 of a branch were filled with mature spores — all being at the 

 same stage of maturity — and the cell walls in process of 

 gelatinization. These bodies were 12. 5 mic. in diameter — in this 

 respect and in their having thick membranes, corresponding 

 to the spores pictured in fig. 11. The spore mother cells were 

 divided into two, and in one case, four portions. They were in 

 the main spherical, but some were angular from being crowded 

 together. They were arranged in an irregular row, or some- 

 times two rows after the manner of the eggs in Sphaeroplea 

 annulina. An accident happened to the specimen before a 

 drawing could be made. 



A third example afforded still more conclusive evidence of 

 the transformation process (PL XXXIII, figs. 12, 13.) The 

 cylindrical vegetative cells were observed in the very act of 

 developing into the Palmella cells. All stages are seen on the 

 same branch. The resulting Palmella cells are 12-20 mic. in 

 diameter. The Palmella cells of the plant described by Cien- 

 kowski were .012 mm. in diameter. In regard to the trans- 

 formation process, the behavior of the plant is similar to the 

 one described by Cienkowski. 



Material from pebble "4," thirty-five days after being taken 

 from the spring, was seen to be forming in great quantity the 

 Palmella cells from the filamentary cells. Large masses of 

 irregular, or spherical, or elliptical bodies were piled together. 

 They varied from 12-20 mic. in diameter. Many were dividing 

 into two and four portions. They were surrounded by wide 

 gelatinous walls. 



Before it was known that the plant was a Stigeoclonium and 

 that this transformation occurred, several references were 

 made in the notes to the effect that a number of times the Pal- 

 mella cells had been observed lying in a position that would 

 indicate they had been borne on a branch, the walls of which 

 had gelatinized. Also, that they occurred in exceedingly large 

 quantities which could hardly be accounted for in any other 

 way than that they were transformed Stigeoclonium cells. 



