VAUCHERIA. 



[ 672 ] 



VEGETABLE KINGDOM. 



sometimes met with having several living re- 

 gions of this kind, shooting out into branches, 

 separated from each other by dead, empty 

 lengths of the filament. 



Besides the vegetative reproduction above 

 described, the Vaucheria are reproduced by 

 spores formed by the concurrence of two 

 distinct kinds of reproductive organs. Fila- 

 ments growing on damp ground ordinarily 

 exhibit lateral organs of two kinds, associated 

 together, but variously grouped and collected 

 in varying numbers at particular points, ap- 

 parently according to external conditions. 

 The larger kind of organ appears first as a 

 pouch-like process, which expands into a 

 squat flask-shaped body, stalked or sessile, 

 the neck of which is gradually turned over 

 in the development, until it projects at one 

 side, the form then somewhat resembling 

 that of a bird's head (or a chemist's glass 

 retort cut off^ short at the neck). Near this 

 on the main filament, or on a common pedi- 

 cel with one or more of the bird's-head or- 

 gans, is developed another organ, at first 

 straight and tubular, but soon curving over 

 into the form of a hook or scroll, without, 

 however, expanding. The expanded part of 

 the bird's-head organ (or sporangium) be- 

 comes filled with dense green granular mat- 

 ter, and cut ofi^ by a septum from the main 

 filament. The upper part of the " hook" is 

 likewise cut ofi^ by a septum, and the con- 

 tents of the apical cell thus formed are of 

 light colour, and soon lose most of the chlo- 

 rophyll. From the association of these two 

 kinds of organ, and the production of spores 

 in the sporanges, it was supposed, as long 

 ago as in Vaucher's time, that they repre- 

 sented sexual organs. Vaucher thought the 

 "hooks" discharged akindofpollen to fertilize 

 the sporanges. Other algologists, especially 

 N'ageli, supposed or asserted that a conjuga- 

 tion took place between them (like that in Spi- 

 rogyra), a view more or less favourably re- 

 ceived until a few years since, when Karsten 

 asserted that he had actually observed it in all 

 its details. But Pringsheim has lately pub- 

 lished a very complete and certainly more 

 trustworthy account of the development of 

 these structures, in which he denies the con- 

 jugation, but asserts that the " hook " is an 

 antheridium, and that when mature it bursts 

 at the apex and discharges biciliated sper- 

 matozoids resembling those of Fucus, which 

 enter the simultaneously opened neck of the 

 sporange and fertilize its granular contents. 

 The contents become isolated from the wall, 

 secrete a proper coat, and form a free cell 



(spore) lying in the sporange, its granular 

 matter gradually losing the green colour 

 and becoming brown. Two coats, at least, 

 are developed, and the spore ultimately 

 escapes by the decay of the parent filament 

 and sporange. According to Pringsheim, 

 about three months elapse before germina- 

 tion, in which process the outer spore-coat 

 splits, and the inner grows out into a tube, 

 forming the basis of a new ramification of 

 the Vaucheria-filiiment. 



In the systematic works on Algology, nu- 

 merous species of aquatic and land Vaucheria 

 are described ; but we agree with Thuret in 

 believing that the characters by which most 

 of the forms are distinguished are unessential, 

 therefore we omit any synopsis of them. 

 Even V. racemosa, Decaisne, appears merely 

 an extreme of the kind of development 

 producing V. geminata. Thuret proposes 

 the name V. Ungeri, to include all but V. ra- 

 cemosa ; Hassall suj^presses the name V. cla- 

 vata, as indicating a form common to all the 

 species, of which he describes a large num- 

 ber. We do not find anything sufficiently 

 distinctive in the characters of the marine 

 species cited by Harvey. 



The admirable essay of Unger should be 

 consulted by those studying the gonidial 

 reproduction. 



BiBL. Vaucher, Conferves d'eau douce 

 (Ectosperma) ; Hassall, Brit. Fr. Alg. ; 

 Harvey, Brit. Mar. Alg. p. 195 ; Unger, 

 Nova Acta, xiii. p. 11, Die Pfianze hn Mom,, 

 der Thierwerdung, Vienna, 1843; Decaisne, 

 Ann. des Sc. nat. 2 ser. xvii. p. 430 ; Thuret, 

 ibid. xix. p. 266 ; Karsten, Bot. Zeitung, x. 

 p. 85 (1852) ; Pringsheim, Ber. Berlin Akad. 

 March 1855; Ann. Nat. Hist. 2nd ser. xv. 

 p. 346 ; Alex, Braun, Verjungung {Bay Soc. 

 Vol. 1853, passim), Alg. unicell. (1855), 

 p. 8, 105; Nageli, Neuer Algensyst. p. 175. 

 pi. 4 ; Itzigsohn, Bot. Zeit. xi. p. 225 (1853). 



VEGETABLE IVORY.— This substance 

 consists of the seeds of the Palm called 

 Phytelephas macrocarpa, composed of a 

 large round mass of bony Albumen, inwhicli 

 a small embryo is imbedded. Slices of this 

 ivory-like albumen, ])laced under the micro- 

 scope, aff"ord very beautiful examples of ve- 

 getable cells with the cavities almost oblite- 

 rated by Secondary deposits (PL 38. 

 fig. 23). 



VEGETABLE KINGDOM.— The large 

 number of natural orders of Angiospermous 

 Flowering Plants and the subordinate cha- 

 racter of their diversities in microscopic 

 structure, lead us to depart from the plan on 



