586 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
were the first to demonstrate the wide distribution and innumerable 
abundance of this unicellular calcareous alga, and I agree with them 
in the supposition that these play a significant part in the biology of the 
ocean and in the formation of its globigerina ooze. 
3. Murracytee.—Under this name I may here refer to the very im- 
portant but hitherto neglected group of planktonic protophytes, which 
were first discovered by John Murray and described under the name — 
Pyrocystis (5, p. 533, plate xx1; 6, pp. 935-938). These “unicellular 
aleve” are transparent vesicles, from 0.5 to 1 or 1.5 millimeters in di- 
ameter, and spherical, oval, or spindle-shaped in form. Their simple 
continuous cell membrane is very thin and fragile, like glass. It is 
stained blue by iodine and sulphuric acid, and seems to contain a small 
quantity of siliceous earth. The contents of the vesicle is a vacuolated 
cell, whose protoplasmic network contains many yellow granules of 
diatomin.. The spherical form (Pyrocystis noctiluca Murray) is very 
similar in size and form to the common Noctiluca miliaris and probably 
is very often mistaken for it. I saw these thirty years ago (1860) at 
Messina, and later (1866) at Lanzarote, in the Canary Islands. 
When John Murray published in 1876 the first figures and careful 
description, he at first placed them with the diatoms, but later (6, p. 
935) he has, with justice, separated them. He there says of Pyrocystis 
noctiluca: 
This organism is everywhere present, often in enormous masses, at the surface of 
the tropical and subtropical oceans, where the temperature is not more than 20° to 21° 
C., and the specific gravity of the oceanic water is not diminished by the presence 
of coast and river water. Pyvrocystis shines very brightly; the light comes from the 
nucleus and is the chief source of the diffuse phosphorescence of the equatorial oceans in 
calm weather. 
Since these unicellular vegetable organisms do not have the char- 
acteristic bivalve shell or siliceous case of the diatoms, but their cell 
membrane forms a completely closed capsule, they can not be reckoned 
with the latter, but must be regarded as representatives of a different 
group of protophytes, for which I propose the name Murracytece or 
‘‘olass bladders” (Murra, a name given by the Romans to a glasslike 
mineral —fluospar (?)—from which costly articles are made.)* 
*In the Atlantic and Indian oceans I have seen great masses of Murracyteaw, and 
have distinguished many species, which may be regarded as representatives of four 
genera: (1) Pyrocystis noctiluea Murray; spherical. (2) Photocystis ellipsoides Hk]; 
ellipsoid. (3) Murracystis fusiformis Hkl (Pyrocystis fusiformis Murray); spindle- 
shaped. (4) Nectocystis murrayana Hkl; cylindrical. The Murracytes multiply, as 
it appears, only by simple division (commonly into two parts, less frequently 
into four). After the nucleus, lying eccentrically or against the cell wall, has 
divided, there follows division of the soft cell body, which is separated from 
the firm capsulelike membrane by a wide space (filled with a jelly). Then the 
membrane bursts, and around the two halves or four tetrads there is immediately 
formed a new covering. Considered phylogenetically, the Murracytes appear as 
very old oceanic Protophytes of very simple structure. Perhaps they ought to be - 
regarded as the ancestral form of the diatoms, for the bivalvular shell of the latter 
could have arisen by a simple halving of the capsule of the former. 
