270 



Fig. 1!J3. 



Corallina officinalis. Border of basal crust 

 in vertical section. 390:1. 



dividing cover cells similar to that pointed out for the articulated fronds and for 

 Lithothamnion by Solms (Corall., p. 27 and 29). The cells of the hypothallium 

 and those of the inner perithallium were, in a specimen collected in July, filled 



with starch grains, while the cells of the outer 

 perithallium showed numerous disc-shaped chrom- 

 atophores and a single nucleus. 



The articulated fronds are connected with the 

 crust by a geniculum. The ramification is mono- 

 podial, ill the typical form pinnate. The branches 

 usually arise near the growing point. At an early 

 stage three (or more) small protuberances are seen 

 at the upper end of the last joint, the middlemost 

 of which develops in continuation of the axis. This 

 has been interpreted as trichotomy, or polychotomy 

 (Kny 1872, Sp. 704, Solms 1881, p. 30) ; I think, 

 however, with Magnus 1872, p. 721, that there is 

 no reason for this interpretation, and that the middlemost outgrowth must be regarded 

 as the principal axis, the others as lateral branches. In f. typica each joint bears two 

 opposite branches, all in the same plane, having for the most part a limited growth, 

 being "pinnulae", but there is no distinct difference between the pinnulae and the 

 longer branches with continual growth. It frequently happens, however, that some 

 joints produce more than two branches; 6 branches are not rarely met with and 

 1 have found up to 10 lateral branches placed in the same plane on the upper 

 border of a much flattened joint (fig. 194 A). More rarely the supernumerary branches 

 are given olf in different directions at the same level, being thus verticillate (fig. 

 194 B, Plate IV fig. 5); in a specimen from Frederikshavn, a whorl of 8 pinnulse was 

 found on a joint. It may happen also otherwise, 

 that normal branches are exceptionally given off 

 in a direction diverging from the ordinary plane 

 of ramification. The joints bearing a great number 

 of branches occur principally in the upper part of 

 the shoots produced in a period of growth. Be- 

 sides the normal branches, adventitious ones occur, 

 though rather rarely (Comp. Solms 1, c. p. 29). Their 

 position is less regular than that of the normal 

 branches, and they are usually given off from the 

 under part of the joints. 



While in the f. typica every joint bears usually 

 two opposite branches, other specimens, especially 

 those growing in deeper water, are less branched, a greater or lesser number of 

 joints bearing no branches, or only one. In these specimens the joints are cylin- 

 drical or nearly so, while the joints of the much branched forms are usually more 



Fig. 194. 



Corallina officinalis. A, seriate branches 

 placed on the border ofajoint. B, upper part 

 of frond with verticillate branchlets. 3: 1. 



