igi6] ROE—SPLACHNIDIUM 401 



strikingly characteristic feature of Splachnidium. The material 

 proved inadequate for the study of reproduction, but furnished a 

 good series for the development and fate of the "apical cell." No 

 mitosis was observed, and hence no chromosome count was possible. 

 It is hoped that some one in the region where Splachnidium grows 

 may be interested enough to investigate material secured at the 

 exact time when cell division occurs, probably at night, or to 

 observe the behavior of the living bodies after discharge from the 

 reproductive sac. 



Origin of the initial row 



The first feature which tends to set the initial cells apart from 

 adjacent border tissue is the taking on of a heavy coat of mucilage 

 (fig. 1). In this and subsequent early stages the heavy mucilage 

 coat is the only character which distinguishes the initial from 

 young vegetative hairs abundant in the apical region (figs. 2-5). 

 A second feature marking this unique structure is the beginning 

 of resorption of cross-walls and loss of original definite nuclear 

 structure (figs. 4, 6, 13, 15). Gradually a complete linear row 

 of cells, reaching entirely through the thallus, is differentiated from 

 the surrounding tissue as an initial row (figs. 5, 7, 8, 13, 15). 



Sometimes there is no evident differentiation of tissue at an 

 early stage, but portions of old apical hairs may assume the heavy 

 mucilage coat (figs. 9-1 1), and there follows an involving of the 

 entire linear row of which the hair is a terminal portion. Part 

 of the old hair may be cast off, eventually leaving only the lower 

 portion (fig. 11). 



By the time an entire linear row is so differentiated, the char- 

 acteristic filiform appendage, which has been described (10) as 

 "growing between the cells of the thallus toward the center of 

 the branch," begins to be evident (figs. 15, 16). Pressure of 

 abutting tissue has narrowed the basal portion into a tail-like process 

 as resorption of old walls and cell contents has gone on, whereas 

 freedom from pressure above has allowed expansion into a pear- 

 shaped oval. At this stage all of the original contents left in 

 the filiform portion consist of granular patches of cytoplasm, and 

 in the oval portion there is a similar granular substance with the 



