586 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



were the first to demonstrate tlie wide distribution and innumerable 

 abundance of this unicellular calcareous alga, and I agree with them 

 in tlie supposition that these play a significant part in the biology of the 

 ocean and in the formation of its globigerina ooze. 



3. Murracytecv.—TJBcler this name I may here refer to tlie very im- 

 portant but hitherto neglected group of planktonic protophytes, which 

 were first discovered by John Murray and described under the name 

 Pyroeystis (5, p. 533, plate xxi; 6, pp. 935^938). These '^ unicellular 

 algcT3"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 veiy 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 {Pyroeystis noctiluca Murray) is very 

 similar in size and form to the connnon NoGtiluca miliar is 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. 



AVhen 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 Pyroeystis 

 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. Pyroeystis shines very brightly ; the light comes from the 

 nucleus and is the chief source of the diffuse phosphorescence of the equatorial oceans in 

 calm Aveather. 



Since tliese 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 lie regarded as representatives of a different 

 group of protophytes, for which I propose the name Murracytecv or 

 "glass bladders" {Murra, a name given by the Eomans to a glasslike 

 mmeral-fluospar(?)— from which costly articles are made.)* 



nn the Atlantic and Indijin oceans I h'^i^^seen great masses of M^^^^^^Zy^^a^i 

 have dis inguished many species, which may be regarded as representatives of four 

 genera: (1) P^,.ocv.s/is „oe/l/«,ca Murray; spherical. (2) Fhotoc„stls elllpsoldes Hkl- 



Bhrer\4?\ r^T''-^'"'-^"''"" "^'^ (pyroeystis fuslformls Murray); spindle: 

 shaped, (i) ^eetacyst,s .H»rm.,««« Hid; cylindrical. The Murracytes mnltLy as 



dWided heie f 1 "r"' '^f ^ eccentrically or against the cell will, hal 

 jjfil *he:e folows division of the soft cell body, which is separated from 

 the firm capsulelike membrane by a wide space (filled with a iellv). Then the 

 membrane bursts, and around the two halves or four tetrads there is immed atdv 

 formed a new covering. Considered phylogenetically, the ^.r.aov/rrpear ' 

 very old oceanic Protopkytes of very simple structure!^' Perhaps they ought to 1 

 regarded as the ancestral form of the diatoms, for the bivalvular shell of ^h latt 

 could have arisen by a simple halving of the -apsnle of the former 



