4 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. 
days, no matter what precautions are taken. On the other hand, with 
good circulation and aeration the ‘walls of the vessel soon take on a 
rich brown color, especially where the air supply is more plentiful. 
The sporelings have slender, club-shaped germ tubes. (Fig. 2, C.) 
In a healthy culture spores may be found germinating six hours after 
the planting of the sporophyls. Many spores floating on the surface 
of the water seem to germinate more slowly, and those that attach 
themselves to the sides of the vessel within 4 inches or less of the 
surface seem to grow the best. 
EARLY STAGES. 
The examination of millions of sporelings has not furnished con- 
clusive evidence of sexuality. Young sporelings have been found 
with their club-shaped ends in contact, but the cell-wall was still in- 
tact between the two plants. They were always outnumbered more 
than 1,000 to 1 by similarly shaped plants whose tips were not in con- 
tact, so it appears to have been a case of chance contact of independ- 
ent plants, and not of fusion of germ-tubes. The germ-tubes usually 
consist of a single cell for the first week or two. Gradually the ter- 
minal portion increases its diameter until many sporelings assume a 
form resembling dumb-bells. The color-bodies, or chromatophores, 
migrate to the enlarged end, leaving the old spore and the slender 
base of the filament colorless. A number of recent observers have 
regarded these plants as male or antheridial plants, but the author 
has found no satisfactory evidence that they are. Minute olive- 
green globules have often been seen in sporelings 1 or 2 weeks old, 
and also moving about in the water in which the sporelings were 
mounted for study, but they have never been seen moving within the 
filaments preparatory to escaping, as the sperms move within the 
antheridia of mosses. 
Furthermore, these bodies that might be regarded as sperms fre- 
quently occur in sporelings that show no thickening. They are also 
commonly associated with an undivided part of the chromatophore. 
They have also been seen in plants that differed greatly in form from 
those regarded as antheridial, and Pelagophycus spores have been 
seen to break up into such bodies even before assuming the globular 
form of resting spores. Their occurrence, therefore, seems merely to 
indicate the death and decay of sporelings. Very commonly a cul- 
ture makes a good growth for two or three weeks and then suddenly 
dies out. The spores seem to germinate readily and pass the first 
stages under conditions not at all favorable for further development. 
With good circulation and aeration at a temperature of 14° to © 
16° C. the sporelings continue to grow for two months or more. The 
enlarged and condensed ends of the dumb-bell shaped sporelings con- 
tinue to enlarge and soon begin to divide, by cross walls, to form 
chains of cells. The color, hitherto olive-green, becomes the char- — 
acteristic brown of Macrocystis. The filaments may become 5 to 10 
cells long and they often branch extensively. (Fig. 2, D.) These 
may be gametophytes or sexual plants, but none has been found giv- 
ing rise to leafy kelp plants, nor has a structure been found in one 
of them that could be identified as an oogonium or egg cell. They 
seem instead to form various fantastic little plants and then die. 
‘Typical kelp plants, or sporophytes, as they are called by those 
who believe them to be of sexual origin, arise from what often ap- 
