20 



paa koloniens alder. Hos h. rioJaceiis faiidt jeg saaledes 

 om vaaren (april-mai) næsten lutter cirkiilære systemer 

 med et i-inge antal individer, om hosten (september — novem- 

 ber) hovedsagelig ellijitiske systemer med indtil 30 indivi- 

 der. Medens der tidlig paa aaret optræder faatallige og 

 ganske .smaa cormi. stiger antallet og størrelsen af disse 

 udover sommeren tor at kulminere i oktober maaned. Tyk- 

 kelsen af cormus er hos denne art forholdsvis constant 

 1 — 2""", formen forovrig vekslende, idet den betinges af de 

 algers eller zostralilades form, hvortil den er fæstet. De 

 sidstes langstrakte form frembringer saaledes baandformige 

 cormi. Paa samme maade synes ogsaa systemerne at af- 

 passe sig efter de lokale forholde, idet de samtidig med 

 koloniens vækst strækker sig i bladets længderetning. 1 

 det liele og store tåget tør man vel gaa ud fra at koloniens 

 alder til en vis grad er proportional med dens størrelse og 

 med antal individer i systemerne. 



Farven er hos denne art saa boist varierende, at man 

 kun med vanskelighed vil kunne tinde to absolut ensfarvede 

 cormi. Det blaa jngmcnt er mest udbredt, det gule mindre 

 hy])pigt og forekommer væsentlig paa den centrale del af 

 individernes ovei'side som et smalere eller liredore baand. 

 Den grønne farve fremkommer altid ved en blanding af 

 blaat og gult pigment. Den rusthrune farve var ulige 

 sjeldnere og mindre udbredt: især omkring in- og egestions- 

 aabningen og ved nervegangliet. Det sidsti' i)igment op- 

 traadte især bos sygelige cormi senhøstes. 



Hvad farvernes relation til aarstiden angaar, vil jeg 

 anføre, at det blaa pigment optræder rigeligst om vaaren, 

 medens det gnle er karak'teristisk for hostformerne, der 

 ved sin pigmentblanding for det blotte øie giver et grønt 

 ellei- giilgront udseende. 



At voksestedet ikke i nogen væsentlig grad betinger 

 farven, vil man se deraf, at de forskjelligste varieteter tin- 

 des fæstede til samme zostrablad i binandens umiddelbare 

 nærhed. 



Senhøstes (december) foregaar der en sterk udskillen 

 af cellulose, som ofte atsættes i smaa klumper paa flere 

 millimeters tykkelse samtidig med individernes gradvise ben- 

 døen. Der forekommer ikke sjelden ved denne aarstid 

 større cormi kun opfyldte af stoloner hist og her med en- 

 kelte yngre knopper eller systemer af saadanne. 



Individernes dimensioner er hos denne art meget 

 vekslende dog forholdsvis ens iiaden samme koloni. Aarsagen 

 hertil maa vel ialfald delvis antages at ligge i forskjellige 

 ernæringsforholde. Individernes form har jeg idetheletaget 

 fundet at være mere langstrakt og smal i cormi med ellii)- 

 tiske end i dem med cirkulære systemer. 



cases on the age of the colony. In B. riolarevs, for in- 

 stance. I found in the spring (Ajiril and ~Mn\) alniost per- 

 fectly circular systems with few members, in the autumn 

 (September to November), principally elUptical systems, 

 with sometimes as many as 30 members. Whereas early 

 in the year tiie cormi are few and quite small, during the 

 summer their number and size increase, to culminate in 

 October. Tiie tbickness of the cormi in tliis species is 

 comparatively constant. from 1 to 2'"'" wbile tiie shajie 

 varies, being determined by tlie sh.ipe of the algæ or Zostra 

 leaves to whicli tiiey are attached. In this way the elonga- 

 ted form of the latter produces riblioii-like cormi. In 

 the same way the systems seem to adapt themselves to 

 local conditions; as they extend simultaneously with the 

 growth of the colonies in the direction of the length of the 

 leaf. On the whole. we may veiitiire to assume tliat the 

 size of the colony and the number of members in its sys- 

 tems, are. to a certain extent, projiortional to its age. 



The colonr in this species is so extreniely variable, 

 that it is difticult to tind two cormi absolutely uniform in 

 that respect. Blue is the most general colour. yeljow less 

 frequent, and occurring for the most pai't an the central 

 portion of tlie njiper side of the niember in tiie form of a 

 broad oi- narrow band. Green is always produccd hy a 

 mixture of blue and yellow. The rusty brown colour was 

 considerably rarer and less ditfused, especially round tiie 

 l)ranchial and atrial apertures and by the nerve-ganglion. 

 The last-named colonr ajjpeared especially in sickly cormi. 

 late in the autumn. 



AVith regard to the relatiou of tiic colour to the 

 season of the year. I may state that the blue pigment ap- 

 pears ])lentifully in the spring, while the yellow is charac- 

 teristic ol autumn forms, whicli with their mixture of pig- 

 ments have a green or yellowish green appearance to the 

 naked eye. 



That the habitat does not to any great extent in- 

 fluence the colour. will be seen from the fact tiiat the most 

 different varieties are found attached to tiie same Zostra 

 leaf. in one another's immediate vicinity. 



Late in the autumn (December), a large secretion of 

 cellulose takes jjlace, it being frequently detaclied in small 

 lumps several millimetres in tbickness, simultaneously with 

 the gradual dying away of the members. Large corrai are 

 not infrequrntly fouud at this time of year ouly filled here 

 and there with stolons. with a few young l)uds or small 

 systems of sucli. 



The (limeiisions of the members in this species are 

 very variable, though comparatively uniform within eacli 

 colony. The reason of this must, jiartly at any rate, be 

 considered due to varied nutritive conditions. I have found 

 the shape of the members, on tiie whole. to be more elon- 

 gated and narrow in cormi witii elliptical systems than in 

 those w'ith circular svstems. 



