362 BOTANICAL GAZETTE [MAY 
length of the chain of cells formed, until in 1 per cent rarely more 
than two cells were found united and growth was very meager. 
If cultures were old, whatever the concentration of the solution 
there was almost a complete separation of the cells, except once 
in a o.4 per cent Knop’s solution, where the plant floated on the 
surface of the liquid, long chains of cells were found. Even in 
the longest chain, however, the connection between the cells 
seemed to be a frail one, the cells becoming dissociated so easily 
that it is a question whether the alga should be called a unicellular 
one or a filamentous one. In this respect it resembles closely 
Stichococcus, which is classified by CHopat (1) as a filamentous 
form, but which probably should be regarded as a unicellular 
alga. 
In what condition this alga existed in its natural surroundings 
it is impossible to say, since it could not be observed on account 
of its minute size; but when first noted in culture, the scattered 
chains consisted of but two or three cells, and indicated that 
when it was put in the culture it was in the unicellular form. 
The direct cause of this fragmentation of the chains or fila- 
ments was not determined, but the process resembled so closely 
a similar fragmentation observed by Kieps (3) in Hormidium 
nitens that the cause is probably the same. Kress observed in 
his cultures of Hormidium that the fragmentation took place 
either in an insufficient amount of nutritive salts, or in absence 
of sufficient moisture, and offers a hypothetical explanation of the 
phenomenon. His theory is that under these conditions the alga 
at first ceases to divide and then ceases to grow, but that nutri- 
tion may continue for some time. As a result, the cell becomes 
filled with organic nutritive material, whereby the walls become 
distended and the layer of cuticula binding the cells together 
becomes broken and the cells fall apart. Livincston (4), how- 
ever, in his work on Stigeoclonium, believed that a fragmentation 
occurred as a result of osmosis, and found that the higher the 
osmotic strength of the nutritive solution the more readily the 
dissociation of the cells took place. 
The phenomenon of filaments falling apart into individual 
cells each of which continues to live, and under favorable condi- 
