274 



EMBEYOGENY IN HEPATIC^. 



In Oharacese, which, are aquatic cryptogamic plants found in 

 ponds, there are two fertilising organs, one called, from its rounded 

 form, the globule (fig. 486 g), corresponding to the antheridium ; and 

 another (fig. 486 m), the nucule (nucula, a small 

 nut), representing the archegonium. The globule 

 contains a definite number of cells, which meet in 

 the centre and form a round mass, whence jointed 

 filaments containing spermatozoids arise (fig. 487). 

 The colour of the globule is red. The nucule is 

 a large oval cell (archegonium), round which five 



Fig. 486. Kg. 487. 



filaments are spirally twisted, ending at the summit in five or ten 

 tooth-like processes. The central oval cell in the nucule is fer- 

 tilised by sperma.tozoids from the jointed filaments of the globule 

 coming into contact with it. After fertilisation the nucule drops 

 off and ultimately forms a new plant. While the nucule may be 

 considered as equivalent to the archegonium, it is in reality a com- 

 bination of that organ and a spore. 



In Hepaticse (Liverworts), including Marchantise and Jungerman- 

 nise, the reproductive organs consist of antheridia and archegonia. 

 The antheridia are small cellular sacs of a globular, ovoid, or flask- 

 like form. They have a single or double cellular covering, enclosing 

 viscid matter, in which are developed four-sided cells, in each of 

 which is a small filiform spermatozoid (phytozoon), rolled up in a 

 circular manner, and displaying rapid movements. The spermatozoids 

 are finally liberated, and unrol themselves, appearing as filaments 

 swollen at one extremity, and gradually tapering to the other. In 

 Marchantia (fig. 488) the antheridia occur in the upper side of an 

 elevated disk or receptacle, r. When this disk is cut vertically, as in 

 fig. 489, they are seen at a a, as flask-like cellular sacs separated by 

 air-cavities, cc, which communicate with stomata, ss.i In fig. 490 

 an antheridium is shown discharging its minute cells containing sperma- 

 tozoids. In some Hepaticae the antheridia occur in the substance of 

 the thallus, while in others (as in some Jungermannise) they 

 appear in the axil of the leaves. 



Mg, 486. CeUular tubes of Chara, with vertioiilate branches, from the axil of -which 

 proceeds the 'nucule, n, containing a germinating spore, while below the branch is placed 

 the red globule, g, containing antheridian cells and spermatozoids. Fig. 487. Filament 

 from the globule of Chara, consisting of numerous sperm-cells (phytozoary cells). A sper- 

 matozoid, s, is seen escaping from one of them. 



