NOTE ON THE VERTICAL DISTRIBUTION OF 
MALLOMONAS. 
G. C. WHIPPLE AND HORATIO N. PARKER. 
MALLomonas is a microscopic organism that is often found 
in the water of ponds and lakes. It usually occurs in greatest 
abundance in the spring and autumn, but occasionally it appears 
at other seasons. It is an odor-producing organism, and as 
such is liable to give trouble in water supplies. Its odor is 
similar to that of Cryptomonas, which has been described as 
resembling “candied violets.” As the odor increases in inten- 
sity it loses its aromatic qualities and becomes “fishy.” In 
addition to its odor it has a slight sweetish taste. Mallomonas 
is not known to have ever given serious trouble in a water sup- 
ply, because it is seldom found in large numbers for any con- 
siderable length of time, but several cases are on record where 
it has been present in water supplies, and where it has undoubt- 
edly caused a noticeable odor. Observations seem to indicate 
that whenever it is present in the water to the extent of about 
500 per cc. its odor may be recognized. However, this paper 
is not concerned with the odor-producing properties of Mallo- 
monas, nor its effect on water supplies, so much as with the 
organism itself, its structure, its development, and especially its 
peculiar, characteristic, vertical distribution in ponds and lakes. 
The earliest description of Mallomonas was that of Perty in 
1852. To him we owe its generic and specific names. Some 
writers have questioned the claim of Mallomonas to rank as an 
independent genus. Stein held that it was but a monad of 
Synura, freed from its colony. Recent observations have es- 
tablished the position advanced by Perty and adopted by Kent. 
Kent’s description of Mallomonas is as follows: 
GENUS MALLOMONAS PERTY. 
Animalcules free-swimming, oval or elliptic, persistent in shape ; cuticular 
surface indurated, clothed with long, non-vibratile, hair-like seta; a single, 
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