M. H. V. Mohl on the Structure uf Chlorojjhyll. 417 



In all tlic cells of the frond of Aathoceros lavis (with tlic ex- 

 ception of the epidermal cells), \vc find a large globular parietal 

 nucleus, within which lie a considerable number (perhaps 100 

 and more) of small, longish starch-grains. This nucleus is en- 

 veloped in a mass of protoj)lasm, which runs out into two or 

 more short, thick, radiating processes applying themselves to the 

 cell-wall, or has the form of a disk irregularly dentate at the 

 circumference, and corresponds to the lines of ciiculating pro- 

 toplasm which in other cells run out from a mass enveloping 

 the nucleus. This entire mass is of a bright green colour, and 

 constitutes the only mass of chlorophyll occurring in the cell. 



In the epidermal cells the form of the chlorophyll-mass is 

 somewhat more complicated. Taken as a whole, it has the form 

 of a thin disk stretching across the cell, parallel to the outer 

 wall of the latter, containing in its centre a large globular nu- 

 cleus, within which lie numerous starch-granules. In young 

 cells, situated near the point of vegetation of the frond, this disk 

 stretches entirely aci'oss the cavity of the cell, and its borders 

 are applied upon the side- walls, so that the cell when seen from 

 above appears entirely green. But in the full-grown cell the 

 margin of this green disk has separated at from four to six 

 places from the wall of the cell, become retracted and at the 

 same time turned up towards the outer w^all of the cell ; so that 

 the disk has now assumed the form of a star-shaped membrane, 

 with from four to six broad rays separated from each other by 

 roundish sinuses, and excavated into the form of gutters on the 

 upper side ; the nucleus lies in the centre of this membrane, 

 projecting strongly into the interior of the cell. 



It is evident that in this plant the mass of protoplasm, which 

 envelopes the nucleus in all plants, acquires a special develop- 

 ment, and that the green colouring matter is connected with it. 

 Whether or not the latter permeates the substance of the nu- 

 cleus I was unable to discover. The protoplasmic mass appeared 

 finely granular; there was no internal movement of its mass 

 corresponding to the rotation of the sap of many cells. There 

 were no starch-grains in the protoplasm, but only in the nucleus. 

 The presence of these starch-granules, and particularly their 

 large number, is a peculiarity of Anthoceros, which is also met 

 with in those nuclei which have no chlorophyll in their vicinity, 

 as, for example, in the epidermal cells of the capsule. 



The alterations undergone by the chlorophyll of Anthoceros 

 through the action of water, correspond entirely to those above 

 described of Zygnema. The chlorophyll-mass swells, with a 

 shortening of its radiating processes, into an irregular globular 

 or ovate shape, the starch-granules lying in the nucleus become 

 at the same time more distinctly visible, while in the interior 



