58 



leiiili/ation (fig. 1). In dried specimens I could not see distinct starch-grains, but 

 only indistinctly limited spols giving blue-yiolet colour with iodine. 



Gonidia seem to occur much more fre([uently than the car|)Ospoi-es on our 

 coasts, as I have met with the species at all seasons and most fre([uently with 

 spores, which must be regarded as gonidia. These spores may 

 arise in very thin threads whose articles show only one longi- 

 tudinal wall, but their origin can also take place in thick 

 threads with numerous longitudinal walls. As a rule two or 

 tour spores are produced by each mother-cell; most frequently 

 I found no starch in these spores, but in a few cases I obser- 

 ved numerous very small starch-grains in spores which were 

 undoubtedly gonidia (Thyboron and Skagen, July). In May I 

 saw the spores escape from threads recently collected at Hirs- 

 hals, a |)rocess that look place very rapidly; amoeboid move- 

 ments I did not observe, but the chromatophore showed alter- 

 ations of foriu. In one spore it had taken a globular form and 

 was sharply defined; shortly afterwards it became angular and 

 seemed about lo lake the ordinary stellate shape, but it soon 

 took again the rounded form. In other cases these spores 

 showed the amoeboid movements. 



This species occurs at oidinary high-water mark and 

 higher, so that it is fre([uently out of the water and even 

 dried up and in great measure only wetted by the spray of 

 the waves. It is therefore easy to understand why it is not 

 commoner than it is at the Danish shores, where Ihe tide is mostly insignificant; 

 in unfavourable periods with continual low water and calm, dry weather it would 

 be in danger and would be killed at all the places, 

 where it is not protected by special conditions against 

 desiccation of long duration. At Frederikshavn it 

 grows chiefly on the outer sides of the moles, whei'e 

 with a westerly wind the level of the sea is pro- 

 portionally high, while with an easterly wind the 

 level is low but the mole ordinarily washed by the 

 waves. The most dangerous condition i'ov the Bangia 

 vegetation is a fairly long period of easterly winds 

 with the wind so light, (hat this vegetation is not 

 reached by the waves, especially when the weather 

 at the same time is bright and dry. Its occurrence 



is therefore very different, not only at various seasons, but also in different years. 

 In winter it is very abundant, but the critical period of the spring will every year 

 kill a greater or smaller part of it and on the duration and intensity of this period 

 depends to what degree that will take place. In summer for examjilc it occurs at 



Fig. 1. 



Bangia fasco-parpurea. Frag- 

 iiiciit ol loiiKilc iilaiiienl with 

 riM lilizatioii lubes and a lew 

 spcinialia slill atlheiinn 



:!iH): 1. 



Fig. 2. 



liaiiijia fuscu- purpurea. Transverse sections 

 of female threads witli eystocarpia. 2(K):1. 



