51)0 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



1. H(iJoHX)li(vrea\ — Under the name Jfalosph(cra viriiJis, Scbinitz 

 (187{f) first described a ne^y genus of green algje from the Mediter- 

 ranean, which a])i)ear tioating in the plankton of the (iulf of Naples 

 in great numbers from the middle of January until the middle of April. 

 They form swimming hollow spheres, from 0.5") toO.Gli nun. in diameter, 

 wliose thin cellulose Avail is covered within by a single laj'er of chloro- 

 phyll containing cells analogous to the blastoderm of the metazoic 

 eg'fi;. Each 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, 1807, at Lanzarote, in the Canary 

 Islands. The hollow si3heres found in the Atlantic are twice as large, 

 and reach a diameter of 1 to 1.2 mm. They have pear-shaped swarm- 

 spores. I named them Halospluvra blastiila. Morphologii*ally these 

 hollow spherical algre. 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 ty])e of the metazoon, so 

 Ealosphan-ii (like Volvox) can be looked upon as the primitive ancestral 

 form of the Metaphyta (1, p. 499). Henseu has lately found numerous 

 living specimens of i/r(?osj)//rtvn, t'/mZi-s 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 suffi(aent for their metabolic activity. 



2. Oscillatoricv. — Like the diatoms in the cold regions of the ocean, 

 the oscillatoriie {Trichodesminm 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 Ked 

 Sea, at Tur, such large quantities of Trichodcsmium erijthueum that the 

 water along the shore was colored blood-red by them. Mobius has re- 

 cently carefully described the same thing anew, and has (quite cor- 

 rectly) traced from it the name of the lied Sea (26, p. 7). Later, T myself 

 found just as great numbers as these in the Indian Ocean at Maledira 

 and Ceylon (25, p. 225). In Eabbe's collections are several bottles of 

 plankton (from the Indian and Pacific oceans) entirely filled with 

 them.* Tlie Challenger found great quantities of Trichodesmium in the 

 Arafura Sea and Celebes Sea (6, p. 545, 007), and also in the Guinea 

 stream (6, p. 218) ; and between St. Thomas ami the Bernnidas (6, p. VM>) 

 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. 



.'i. Snrgassefv. — The higher algjr are represented in the planktonic 

 flora only by a single group, the Sargassece, and these again are com- 



*In tho collection of Jiadiolaria, -which may ho purchased from the fanmlus Franz 

 Pohlo, at Jena, preparation No. 5, from Madagascar, contains many Hakes of this 

 OsciUatoria. 



