KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 61. N:0 II. 41 



I ha ve examined a number of verv small plants, measuring only O.ö to 1,5 mm 

 in length. The smallest are cylindrical and solid, the somewhat older ones have a 

 swollen and a little hollow distal end. The holdfast is formed by a multitude of 

 rhizoids. Fig. 16a shows the smallest plant in optical section. There is no initial: 

 the cell h is perhaps an »apical cell», and I think that it gives rise to a terminal 

 hair, the beginning of the terminal cryptostoma. for in other plants we find an apical 

 hair (fig. 16 b), apparently a continuation of a central row (?) and sunk into a narrow 

 pit by the growth of the surrounding tissue (fig. 16 c). Låter, other cells are pro- 

 longed into hairs and a terminal hair-pit is formed, which is present in every frond 

 examined. Possibly there is at first a subapical meristem soon replaced by inter- 

 calary divisions. New fronds spring from the basal disc (fig. 16 d). In fig. 16 e, 

 where the frond has attained its pear-shape, there is still only the primary hair-pit, 

 and no trace of other crj-ptostomata. The longitudinal growth is, at first, rather 

 uniform : låter, a differentiation in stipe and vesicle takes place and the growth of 

 the former becomes much slower. 



If we compare Adenocystis with Chorda (see Kylin, Entwickelungsgesch. der 

 Phaeophyc.) we shall find a certain likeness between them. Unfortunately the earl- 

 iest stages of the former are unknown. It is probable that it starts as a monosi- 

 phonous filament and develops into a short, polysiphonous body. In the young sporo- 

 phyte of Chorda an apical hair is found, but no cryptostoma. There is also, if my 

 interpretation is correct, no principal difference between Adenocystis and a young 

 Laminaria (see f. inst. Yendo, Development). 



If U triculidium is the sexual generation of Adenocystis, this has, of course, 

 nothing to do with the Laminariacese. And Adenocystis might equally well be cora- 

 pared with Scytosiphon or other members of the same assemblage; there is not much 

 difference between the young sporophyte of Chorda and the young gamophyte of a 

 Scytosiphon pygmceus (Reinke, Atlas Taf. 14). From the comparison of such stages 

 alone no safe conclusions on the affinity can be drawn. 



The structure of the cortex in the mature frond of Adenocystis seems to be 

 variable. Kjellman (Adenocystis-former) pointed out the difference between plants 

 from New Zealand and from Tasmania, the latter having a thicker cortex with the 

 cells arranged in regular radial rows. Kutzing's A major from Kerguelen does not 

 show such conspicuous cell-rows (Tab. phyc. VIII tab. 16). Gain's illustration (Flore 

 algol. p. 46) agrees very well with Kjellma:s ; s fig. 10, of a New Zealand plant. For 

 comparison, I have added fig. 16 f of a Falkland specimen, where also the develop- 

 ment of sporangia and assimilators is seen. Cultures of the spores will reveal whether 

 Adenocystis belongs to the Laminariacea?, or rather to the Chordaceae of Kylin, or 

 if U triculidium and Adenocystis are two generations of the same species, which ranges 

 with the somewhat heterogeneous Encoeliacea?. 



Distribution: Subantarct. Amer., Falkl., S. Georgia, Kerg., Tasm., N. Zeal., 

 Auckl. and Campbell Isl., S. Orkn. Isl., Graham Land. 



K. Sv. Vet. Akad. Handl. Band 61. N:o 11. 



