3S2 



ORGANOGRAPHY. 



Fig. 816. 



Fig. 817. 



number of cells radiating from a central cell. The valves are 

 crenate or toothed at their margins, by which they become 

 dovetailed as it were, with the adjoining valves. From the 

 centre of each valve an oblong cell ( fig. 815, c) is given off in 

 a perpendicular direction. The ei>iht cells from the eight 

 valves converge in the centre of the globule, and are united at 

 their extremities by a little cellular mass. A ninth cell of a 

 similar form, but larger than the others, joins them in the centre; 

 this is the stalk which fixes the globule to the branch upon 

 which it is placed, and which enters its interior by penetrating 

 between the four lower valves. From the point where the nine 

 cells meet, numerous confervoid filaments are given off (^fiy. 

 815, fil), in each cell of which is produced a spiral spermatozoid 

 or antherozoid (fig. 814), each of which is furnished with 

 two very long ciliae of excessive fineness. These ultimately 

 escape from the cell by a sudden movement resembling the 

 action of a spring, and may then be seen to exhibit active 

 movements in water. M. Thuret (from whose description the 

 above account of the globule is condensed), considers the sper- 

 matozoids of the Charas to be unquestionably of the same nature 

 as those of Mosses. 



The nucule or spore is by some considered as a pistillidium. 



It is an oval sessile body, situated 



in the axil of a branch (figs. 



813, n); it consists of a central 



:_^, sac containing protoplasm, oil, 



/^ and starch granules {fig. 817), 



surrounded by five cells, which 



are wound spirally round it, and 



terminating above in five or ten 



smaller cells, the ends of which re- 



, ,;,:^J.v-^.,. main free {fig. 816, a), and thus 



'■^^^0piiil^ form a kind of crown at the apex 



Fig. 816. Nucule of Chara. a. Apices of the nuculc. At an early Stage 



of the spirally wound cells Fig. of growth the cells are Separated 



817. Vertical section of the nucule c t, ..u i i :^ 



oi Chara. from each other, and a canal is 



thus left between them extending 

 from the crown towards the central cell. This canal is sup- 

 posed to form a passage, by means of Avhich the spermatozoids 

 reach the central cell of the nucule. Ultimately the nucule 

 drops off, and germinates in a manner closely resembling a 

 Monocotyledonous Plant, by which a new plant is formed. No 

 intermediate pro-thallus is produced. 



Section 2, — Reproductive Organs of Thalloqens. 



The Thallogens may be divided into three large groups, called 

 respectively, Lichenes, Fungi, and Algaj, each of which again 

 comprises a number of subordinate divisions. The general 

 characters of these will be described hereafter in Systematic 



