LYCOPODIE.E. 



[ 484 ] LYMPHATIC SYSTEM. 



gradually elevated on a thread-like stalk, 

 and separate, disi^laying two terminal buds 

 between them, whence the first bifurcation 

 of the stem proceeds. 



Thismodeofreproductionallies the family 

 very closely to the double-spored JMarsi- 

 leaceas, and separates them from the Ferns 

 and Equisetaceat), in which the protliallium 

 is formed outside the spores, after the ger- 

 naination of the single and only kind of spore 

 which these plants possess. And by recent 

 authors, the Lj^copodiacese are separated 

 from the Selaginacese, on account of the 

 isosporous fructification of the one, and the 

 heterosporous fructification of the otlier. 



The order Lycopodiacete is divided into 

 two families, in accordance with the struc- 

 tui-e of the sporanges : 



Fmnilies. 



Lycopodie^. Sporanges simple, one- 

 celled, 



PsiLOTE^. Sporanges compound, many- 

 celled. 



BiBL. Hofmeister, Verc/l. Unters. 1851, 

 111; De Bary, Ann. Sc. Nat. 4 ser. ix. 30, 

 An7t. N. H. 3 ser. iii. 189; Faukhauser, 

 Bot. Zeit. 1873; Strasburger, Bot. Zeit. 

 1873 ; Sachs, Bot. 474. See also Isof;tes. 



LYCOPODIE'^E.— A family of Lycopo- 

 diaceous plants, distinguished by their 

 simple one-celled sporanges. The existing 

 kinds are all herbs, mostly creeping over the 

 ground ; but some of the fossil kinds, met 

 with especially in the Coal-measures, were 

 large trees, the Lepidodendra. Genera: 



Lycopodium. Sporanges all of one kind, 

 containing numerous small spores resem- 

 bling pollen-grains. 



SeUir/inella. Sporanges of two kinds, the 

 greater part resembling those of Lycopo- 

 dium ; one, situated at the base of the spikes, 

 larger, often four-lobed, and containing only 

 four large spores. 



LYCOPO'DIUM, Linn.— A genus of Ly- 

 copodieae. This has been sufficiently cha- 

 racterized under the head of Lycop(>diace8e. 

 There are more than half-a-dozen British 

 species, mostly alpine plants ; but L. inirn- 

 datmn occurs on bogs in all parts of Britain. 



BiBL. Hook, Br. Ft. ; JBabinglon, Bi-. 

 Bot. ; Francis, Br. Ferns^ 8ic. See also 



LYCOPODIACEiE. 



LY'GEUM, Linn. — A genus of Grami- 

 naceaj ; L. spartum is Esparto-grass. 



LYGO'DIUM, Swarlz.— Agenus of Schi- 

 zasaceie (Polypodiaccous Ferns), consisting 

 of beautifid climbing plants, with conju- 



gate, palmate, lobed, or pinnate leaves, 

 having the sessile sporanges in double rows 

 on the teeth of the pinnules (fig. 437), each 



Fig. 437. 



Lygodium retieulatum. 

 Portion of a leaf, with fertile pinnules. Nat. size. 



having a hood-like special indusium ffia'S. 

 438,439). ° 



16 sp. ; tropical. (Hook, Syn, 437.) 



Fij?. 438. 



Fig. 439. 



Lygoclium retieulatum. 



Fig. 43S. Tooth of a pinnule with overlapping indusia. 



Magn. 2U diams. 

 Fig. 439. The same, with the indusia removed to show 

 the sporanges. Magn. 20 diams. 



LYMPHATIC SYSTEM.— This consists 

 of the lymphatic or absorbent vessels, and 

 the lymphatic glands. 



The lymphatic capillaries commence in 

 the various tissues and organs, as fine net- 

 works or irregular lacunoe. The lacunse are 

 connected by canals and clefts, and form a 

 h'mph-canalicular system. The Ivmphatics 

 of the intestines — the lacteals, commence as 

 cseca. 



In structure the lymphatics resemble the 

 veins, but the walls are thinner in propor- 

 tion to their calibre ; they are also fur- 

 nished with valves, formed by folds of the 

 inner and epithelial coats. 



Tlie Ivmpliatic capillaries are larger tlian 

 the blood-capillaries. At the surface of the 

 serous membranes, the lymphatics are cun- 



