590 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
1. Halospheree.—Under the name Halosphera viridis, Schmitz 
(1879) first described a new genus of green alge from the Mediter- 
ranean, which appear floating in the plankton of the Gulf of Naples_ 
in great numbers from the middle of January until the middle of April. 
They form swimming hollow spheres, from 0.55 to 0.62 mm. in diameter, 
whose thin cellulose wall is covered within by a single layer of chloro- 
phyll containing cells analogous to the blastoderm of the metazoic 
egg. Hach of these epithelial cells divides later into several daughter 
cells, each of which forms four cone-shaped swarm-spores with two 
ciliated cells. I have known this green ball for thirty years. In Feb- 
ruary, 1860, I found them numerous in the plankton of Messina. I 
observed a second kind in February, 1867, at Lanzarote, in the Canary 
Islands. The hollow spheres found in the Atlantie are twice as large, 
and reach a diameter of 1 to 1.2mm. They have pear-shaped swarm- 
spores. I named them Halosphera blastula. Morphologically these 
hollow spherical alge are of great interest, since they are directly com- 
parable to the blastula (or blastosphere stage) of the metazoic embryo. 
As the latter is to be regarded as the simplest type of the metazoon, so 
Halosphera (ike Volvox) can be looked upon as the primitive ancestral 
form of the Metaphyta (4, p. 499). Hensen has lately found numerous 
living specimens of Halosphera viridis in five hauls from a depth of 
1,000 to 2,000 meters (10, p. 521). The light of the bathybic luminifer- 
ous animals may possibly be sufficient for their metabolic activity. 
2. Oscillatorie.—Like the diatoms in the cold regions of the ocean, 
the oscillatoriz (Trichodesmium and its allies) are found in the warm 
regions in inconceivable quantities. It is very certain that the latter, 
as well as the former, belong to the most important source of the 
‘‘fundamental food supply.” Ehrenberg in 1823 observed in the Red 
Sea, at Tur, such large quantities of Trichodesmium erythreum that the 
water along the shore was colored blood-red by them. Md6bius has re- 
cently carefully described the same thing anew, and has (quite cor- 
rectly) traced from it the name of the Red Sea (26, p. 7). Later, I myself 
found just as great numbers as these in the Indian Ocean at Maledira 
and Ceylon (25, p. 225). In Rabbe’s collections are several bottles of 
plankton (from the Indian and Pacific oceans) entirely filled with 
them.* The Challenger found great quantities of Trichodesmium in the 
Arafura Sea and Celebes Sea (6, p. 545, 607), and also in the Guinea 
streain (6, p. 218); and between St. Thomas and the Bermudas (6, p. 136) 
wide stretches of the sea were colored by it dark red or yellowish brown. 
Murray found it only in the superficial, never in the deeper layers of 
the ocean. 
3. Sargassee.—The higher alge are represented in the planktonic 
flora only by a single group, the Sargassee, and these again are com- 
*In the collection of Radiolaria, which may be purchased from the famulus Franz 
Pohle, at Jena, preparation No. 5, from Madagascar, contains many flakes of this 
Oscillatoria. 
