324 C lei and . — The Cytology and Life-history of 
material was collected by the writer during the summer of 1917, at Wood’s 
Hole, Mass., and vicinity. Three fixing reagents were employed— weak 
Flemming, weak chromacetic, and Merkel’s fluid. The two latter were 
tried primarily as aids in the study of chromatophore structure, and for 
nuclear studies proved to be decidedly inferior. Fixations were made at 
all hours of the day and night, both in the field and in the laboratory. 
Some of the material was fixed at ordinary temperatures, some at close 
to o° C. The latter material showed no improvement over the former. 
Stages in the germination of carpospores were obtained by placing 
fruiting plants in shallow vessels in sea-water where the spores were shed 
for a number of hours. By scraping the bottoms of such dishes, a wide 
range of stages was obtained. Spores were also collected on slides laid in 
the bottom of dishes under fruiting plants. 
Most of the material was embedded in paraffin and sectioned at 3 \x. 
Some was mounted whole, either in glycerine jelly, or fixed to the slide 
with Meyer’s albumin, then stained and mounted in balsam. HeidenhaiiVs 
hacmatoxylin was the stain chiefly used. Experiment proved the following 
procedure to be the most satisfactory for sectioned material : 4 per cent, 
iron alum, 8 hours ; running water, 5 minutes ; Heidenhain’s haematoxylin, 
| per cent, water solution, 3d to 48 hours ; running water, 5 minutes ; 2 per 
cent, iron alum until sufficiently destained. With weaker treatment the 
chromatic structures failed to take the stain strongly enough to give proper 
differentiation. 
Vegetative Structure. 
Although the vegetative structure of N emotion is well known, a short 
account of certain details of anatomy and development should be given. 
The thallus consists of a central core of closely intertwining and branching 
threads from which radiate out in continuous series tufts of branching 
assimilative filaments. 
The strands of the central core are largely made up of long, attenuate 
cells, in which I could find neither chromatophore nor nucleus, and which 
apparently serve to support and hold together the tufts of assimilative 
filaments. The tips of these strands, however, are actively growing and are 
found scattered throughout the region of the core, but especially in the 
younger parts of the plant. From these tips new assimilative filaments 
and new cells of the central core threads are developed in rapid succession 
(Text-fig. 1). The cells of these actively growing tips are short, thin- 
walled, and have a nucleus, but no chromatophore (Fig. 7). The strands 
lengthen by division of the apical cell and the branches which develop from 
them arise as lateral buds from cells near the apex (Text-fig. 1, b). As the 
cells become removed from the growing tips, the nuclei are less evident 
