58 PROCEEDINGS OF THE AMERICAN ACADEMY 



usually have protuberances of the same size and shape, and the 

 protuberances of all these cells are usually in the same vertical row 

 or rows. This gives the protruding filament, when seen in side 

 view, the appearance of being straight and unmodified along one 

 margin, but more or less irregularly nodose along the other (cf. Figs. 

 3 and 11). 



As the protuberances increase in size and begin to elongate, they 

 become separated from the parent cell by a tangential wall. These 

 side cells form two or three new cells at .their tips by a sort of 

 budding process. Two or three small papilla? make their appearance 

 on the free end of the cell, gradually increase in size, become con- 

 stricted, and are finally cut off by a division wall (cf. Fig. 4). Each 

 of the new cells proceeds to grow in a similar fashion, and so Me 

 soon have developed from each protuberance a di- or trichotomously 

 branched ramellus, which spreads out in all directions from the point 

 of attachment. During this process, new protuberances have been 

 developing on the same cells with those first formed, and have also 

 been growing out into ramelli, so that finally each cell of the main 

 filament has several (in most cases four) ramelli attached to it. As 

 the ramelli elongate, the basal cells increase in size, and as their basal 

 diameter increases they occupy more and more of the circumference 

 of the parent cell, until, when well developed, they completely encircle 

 it. The four ramelli then form a whorl, each ramellus being situated 

 at right angles to its neighbor. 



During the process of the formation of the ramelli, the axis has 

 been actively growing, new cells have been forming at the tip, and 

 the older cells of the axis have been elongating upwards. As these 

 cells elongate, the whorls of ramelli remain at the very uppermost 

 portion. As the main cells elongate, they also become somewhat 

 swollen, and hence moniliform, there being a constriction formed at 

 the junction of two cells. Consequently the basal cells of the ramelli, 

 since they are situated on the extreme upper portion, are attached 

 to one side of this constriction. As they enlarge, they necessarily 

 touch the other side of the constriction with a portion of the lateral 

 wall, and grow to it. In this way the basal cells of the ramelli 

 become attached to two cells of the axis. The point where two axial 

 cells join may conveniently be called the node, and the axial cells 

 themselves may be termed the internodes. 



The ramelli undergo several important changes as they develop. 

 At first, the cells composing them are all small and nearly of the same 

 size and shape. They are also provided with large and solid chro- 



