205 



A quantity of the material was put into a shallow dish of distilled 

 water and placed in a north window in an attempt to cause it to con- 

 jugate, but indications of an unhealthy condition soon became apparent. 

 As a first indication of this condition the chlorophyll bandK became more 

 slender and the pyrenoids very prominent. Soon after this the filaments 

 began to break up by the decay of some of the cells, so that but few seg- 

 ments could be found that were more than seven or eight cells in length. 

 and the majority of them, were made up of but one or two cells. In the 

 meantime these cells that seemed to have greater vitality began to develop 

 a number of branches as shown in Figs. 1 and 2. The cytoplasm usually 

 followed out into these branches, often taking a loop or an end of a 

 chloroplast with it. In many filaments that showed the peculiarity the 

 branches all arose from the same end of the cells, suggesting a continua- 

 tion of the condition of base and apex that was made so evident by the 

 highly specialized basal cells of the younger plants. So far as was ob- 

 served, the branches always remained continuous with the cells from 

 which they arose, no new cells being cut off on branches. Filaments of 

 other species of Spirogyra often broke up into segments on being put into 

 similar conditions, but no branching was observed. 



The decay of the plant was probably started, in some instances at least. 

 and very evidently greatly aided, as soon as the vitality of the alga had 

 lieen slightly impaired, by the growth of a fungus, Aphanomyces pfoyco- 

 philus De Bary, one of the few parasitic forms of the Saprolegniaccir, 

 which has already been described (5). Other species of Spirogyra seemed 

 immune to the attack of this fungus. 



In some conjugating material of this same species of Spirogyra similar 

 physiological peculiarities were noted. This latter material had been 

 preserved for class use, and the exact locality of its collection is nut 

 known, but it was probably found in the same general locality as was that 

 first mentioned. The filaments of this material showed also, but in a 

 less marked degree, the same unhealthy condition. Some typical branches 

 found are shown in Fig. 4. These branches seemed to serve as "hold- 

 fasts" for attaching the filament to other filaments of Spirogyra or prob- 

 ably to other things in the water. 



Any attempt to get at the meaning of the branches found in either 

 instance must maintain a degree of consistency with two or three promi- 

 nent points observed. The branching described is associated with a 

 pathological condition and is characteristic of this to a more marked 



