u CHARACEM. 



transparent tinely granular terminal papilla, the receptive portion ; the apical cell of the 

 nucule has therefore become transformed into an oosphere. The five enveloping tubes 

 are from the first in close contact with the apical cell or oosphere; after each has 

 become divided by a septum about half way up, the uppermost of the cells thus separated 

 also become closely united with one another above the oosphere. This closing of the 

 envelope takes place at least in Charaf(Etida, before the ' Wendungszelle' has separated 

 from the oosphere. The five upper cells of the envelope are at first as long as the 

 five lower ones, and the septa which separate them lie about half way up the oosphere. 

 As it now increases in size, the five lower ones become elongated into long tubes, which 

 are at first straight but afterwards wind spirally round the oosphere. The five upper 

 cells form the crown, which is elevated some distance above the apex of the oosphere. 

 Between the crown and the apex of the oosphere the enveloping tubes grow inwards 

 and increase in breadth, so that together they form, above the apical papilla of the 

 oosphere, a thick diaphragm open only in the middle, by which a narrow space lying 

 below the crown is separated from a still narrower one above the oosphere. The cells of 

 the crown form a closed cover above the upper space ; the upper and under space are 

 united through the narrow opening in the diaphragm. De Bary found a similar struc- 

 ture in Nitella. As soon as the nucule attains its full size, the small space above the 

 diaphragm enlarges, while the tubes between the diaphragm and the crown grow longer. 

 This piece of the envelope, which only attains its full size at a later period, _De Bary 

 calls the Neck. The sacs now separate laterally from one another, forming five clefts 

 below the crown and above the diaphragm. Through these clefts the antherozoids 

 force their way in great numbers into the apical space, which is filled by a hyaline 

 mucilage. That one or more of them even find their way into the oosphere is rendered 

 the more certain by the fact that about this time its papilla is protected by a very 

 weak cell-wall or has none at all, as is shown by the small pressure required to expel 

 its contents into the apical space. It may therefore be considered as demonstrated 

 that the apical cell of the nucule is actually the oosphere of Gharaceae. 



A. Braun's description of the morphological value of the nucule of Chara is fully 

 confirmed by our Fig. 210, A. It is necessary to explain, in the first place, that this 

 is the lower part of a young fertile leaf oi Chara fragilis, together with the contiguous 

 piece of the stem, and an axillary bud represented in longitudinal section ; m is half of 

 the nodal cell of the stem, i its upper, i its lower internode, sr a descending, y an ascend- 

 ing cortical lobe ; sr the cortical lobe of the lower internode which descends from the 

 leaf, rK a node of it ; i" the first internode of the axillary bud which rests upon the 

 cell n that unites the nodal cell m with the basal node of the leaf. The leaf shows its 

 three lower internodes, 2, a, «, still rather short ; they eventually attain from 6 to 8 

 times this length. Between them are the nodal cells w, nv ; v, v are the cells which 

 unite the leaf-node with the basal node of the leaflet ^ on the outer side of the leaf ; a 

 the corresponding cells on the inner side of the leaf; l?r the cortical lobes of the leaf, 

 two of which go upwards and two downwards from each leaflet /S; the lowermost 

 internode of the leaf is however covered only by descending lobes ; by the side of one 

 of them stands the stipule s. x, x are the cortical lobes which descend on the inside 

 of the internodes of the leaf, where the leaflets are transformed into globules, a, a ; the 

 ascending cortical lobes of the leaf are here absent, because one nucule always springs 

 from the basal node of each leaflet. (Compare with this Fig. 204, A and B.) In 

 reference to the origin of the nucule, A. Braun says {I.e. p. 69) that it springs from 

 the basal node of a leaflet just as the branch does (in Chara fragUis from the basal 

 node of a globule which stands in the place of a leaflet). As in the leaf which subtends 

 a branch the ascending cortical lobes are wanting, so also in the leaflet which bears 

 the nucule the cells forming the ascending portion of the cortex are also wanting. As 

 it is the first leaf of the whorl on the stem that produces a branch in its axis, so it is 

 also from the first (inner) leaflet of the whorl on the leaf that the nucule originates. 

 The basal node of the globule in C. fragUis has, according to A. Braun, not four 



