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MacMillax : Observations ox Nereocvstis 281 



eter, the leg and foot of the stocking each being'T5 liilc. in length. 

 Just above the area of affixation numerous transverse partitions 

 are visible in the fundamental tissue of the disc and apparently 

 there is here a layer ■ somewhat similar to the cambial zone of 

 higher plants and by it the primitive disc becomes thicker. At the 

 same time divisions in various planes cross the more internal cells 



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of the fundamental tissue and the epidermal cells increase in num- 

 ber by vertical divisions. As elsewhere in the plant the epidermal 

 layer of the primitive disc is abundantly provided with chromato- 

 phores, which in my aniline-water-safranin preparations are stained 

 deeply, while the fundamental tissue cells are given a pink hue by 

 the staining of their thin walls. At this a<ie the mar^rin of the 



t>"- ^^*v. — WJ_, 



primitive disc has not yet become crenate, although the slight 

 irregularities of its circular form will in older material bring about 

 the crenations of the margin which eventually protrude themselves 

 -as the primitive hapteres. While the primitive disc is in the con- 

 dition just described, the medulla of the stipe is sharply distin- 



I 



guished from the cortex by its longer and narrower cells, but the 



■ 



differentiation of sieve-tubes and pith-web has not yet taken place. 

 Rather is the whole area of the stipe made up of prosenchymatous 



I 



prismatic cells without intercellular spaces and the cortex consists 



I 



of cells quite similar but considerably shorter. I am not able to 

 distinguish any differences between the epidermal cells of different 

 parts of the plant in this stage of its growth. 



Origin of the secondary Ha/^ttrcs. — Longitudinal sections 

 through the stipe of a plant 1 2 cm. in length j ust above the primitive 

 disc which has now increased in diameter to 5 mm., show the origin of 

 the first secondary hapteres. I am not able to make a distinction 

 between a rhizogenous area of the stipe and the rest of that organ, 

 for as has been previously said, callosities which I consider equiva- 

 lent to secondary hapteres may, under favorable conditions, be 

 produced all the way up the stipe to the pncumatocyst. Those 

 hemispherical emergences of the cortex which are produced close 

 to the primitive disc develop as hapteric branches. The first ap- 

 pearance of the hapteres is as a slight swelling of the cortex and 

 it will be found that this swelling is due to the more activ^e divis- 

 ions of a cambial layer lying between the central cylinder, now 

 very distinct, and the epidermis. Soon this swelling becomes 



