MacMillan: Observations on Nereocvstis 275 



upon Foslie's plates. It is certainly striking and even more so 

 when still younger material is compared. I do not know what 

 precautions Miss Lennebacker took in the selection of her series, 



w 



but from Professor Farlow's observation that the stipe is slender 

 and s/ior/ I should think that possibly some Laviinaria sporelings 

 might have been included. My own researches have shown that 

 in Ncrcocystis plants only one millimeter in length the stipe is 

 ncarl}' as long as the lamina while in plants three 'centimeters long 

 the stipe is five millimeters in length, showing an early, rapid 



elongation of the lamina. I 



General Stnictiuw — The general organography of Ncrcocystis 

 may be best explained by describing the plant as made up of two 

 principal areas — a proximal, affixed portion and a distal free por- 



I 



tion. At first when the plants are merely elongated pear-shaped 

 bodies less than .i mm. in length (as probable from the examina- 

 tion of material that I am yet compelled to consider doubtful) the 

 holdfast or proximal portion is spread out as a disc-shaped foot 

 from the underside of which numerous rhizoid-protuberanccs are 

 affixed to the substratum, while the distal portion enlarging apically 

 is still of a generally cylindrical shape. This primitive holdfast or 

 '* primitive disc'* recalls the similar structure described for young 



L + 



Specimens of Saccorldza dcnnatodca by Professor Setchell and for 

 ' Laniinaria by Foslie. . As in Saccorhiaa the primitive disc is pro- 

 vided with a crenate margin which becomes lobed and the lobes 

 develop into protuberances which may be termed the primitive 

 haptcres. Later when the plant is a centimeter or more in height, 

 but sometimes not until four or five times as long, the secondary 

 hapteres begin to show themselves as rows of emergences just 

 above the point where the primitive disc passes over into t,he 



I 



distal portion of the plant. These secondary marginal hapteres 

 flatten themselv^es where they come in contact with the substratum 



I 



and the whole primitive disc develops into a sucker-shaped cup. 

 Above the first secondary hapteres others commonly develop, the 

 number of emergences in the broken whorls being somewhat 

 variable, but in general each emergence stands over an emer- 

 gence of the whorl below. In this way, finally, a large hapteric 

 area, the '' holdfast/' is developed consisting of hundreds of dicho- 

 tomously branched cylinders and forming a ramose body more 

 than a foot in diameter. 



