CONFERVOIDE^E. 



[ 163 ] 



CONIFERS. 



cells with green, red, or yellowish contents, 

 spherical or elliptical form; the simplest 

 being isolated cells (found in groups of two, 

 four, eight, &c. in course of multiplication) ; 

 others permanently formed of some multiple 

 of four ; the highest of compact, numerous, 

 more or less closely conjoined cells. In- 

 creased by division, or by zoospores bearing 

 two cilia, formed from the coloured cell- 

 contents, set free by the solution of the jelly 

 in water. The zoospores devoid of a mem- 

 brane, at first moving actively, then coming 

 to rest, and acquiring a membranous coat. 

 Some species green and red in different 

 stages. 



11. DESMIDIACE.E. Microscopic, gela- 

 tinous plants, of a green colour, growing in 

 fresh water, composed of cells, devoid of a 

 siliceous coat, of peculiar forms, such as 

 oval, crescentic, shortly cylindrical, or cylin- 

 dric-oblong, &c., with variously-formed rays 

 or lobes, giving a more or less stellate form, 

 presenting a bi-lateral symmetry, the junc- 

 tion of the halves being marked by a division 

 of the green contents; the individual cells 

 either free, or arranged in linear series, col- 

 lected into faggot-like bundles, or in elegant 

 star-like groups, which are imbedded in a 

 common gelatinous coat. Multiplied by 

 division and by spores produced in sporangia 

 formed after the conjugation of two cells 

 and union of their contents, and by zoo- 

 spores. 



12. DIATOMACE^. Microscopic cellular 

 bodies, growing in fresh, brackish, and sea 

 water ; free or attached, single or imbedded 

 in gelatinous tubes, the individual cells 

 (frustuks) with yellowish or brownish con- 

 tents, and provided with a siliceous coat 

 (lorica) composed of two usually symmetrical 

 valves, variously marked, with a connecting 

 band or hoop at the suture. Multiplied by 

 division and by the formation of new larger 

 individuals out of the contents of conjugated 

 cells ; perhaps also by spores and zoospores. 



13. VOLVOCINE^E. Microscopic, cellular, 

 freshwater plants, composed of groups 

 of bodies resembling zoospores, connected 

 into a definite form by their enveloping 

 membranes. The plants (families) areformed 

 either of assemblages of coated zoospores 

 united in a definite form by the cohesion of 

 their membranes, or of assemblages of naked 

 zoospores enclosed in a large common invest- 

 ing membrane. The individual, zoospore- 

 like bodies with two cilia throughout life, 

 perforating the membranous coats, and by 

 their conjoined action, causing a free move- 



ment of the entire group. Reproduction : 

 by direct division or by spores, which are 

 thin-coated and active, or thick-coated and 

 motionless, according to external condi- 

 tions. 



BIBL. See under the Families. 



CONIDIA. The name applied by Fries 

 to the stalked spores or reproductive cells 

 produced directly from the mycelium of 

 many Fungi : characteristic of the Coniomy- 

 cetes. Late discoveries have rendered the 

 term of somewhat equivocal value, and it is 

 not yet sufficiently distinguished from the 

 organs called STYLOSPORES and SPERMA- 

 TIA. Physiologically, they are regarded as 

 equivalent to the gonidia of Lichens. 



CONIFER^. A class of Gymnosper- 

 mous plants, so called from the peculiar 

 form of the female inflorescence, in which 

 the flowers are collected into imbricated 

 cones ; this is the case at least in the Abie- 

 tineae and Cupressineae ; in the Taxinese, 

 which are separated by some authors, the 

 female flowers are solitary. These plants 

 are remarkable in many respects. The pro- 

 cesses occurring in the fertilization of the 

 ovules are quite different from those in the 

 Angiospermous flowering plants, and form 

 a link with the conditions in the higher 

 Flowerless plants. (See GYMNOSPERMIA.) 

 The pollen is of a remarkable form in the 

 Abietineae. The most striking point, how- 

 ever, in relation to the microscopic structure, 

 is the condition of the stems of these plants. 

 The wood is entirely composed of prosen- 

 chymatous cells, of large size, without inter- 

 mixture of ducts or vessels, and those walls 

 of the cells parallel with the medullary rays 

 (very rarely those at right angles) are marked 

 with one or more rows of the peculiar bor- 

 dered pits, which have been wrongly called 

 glands (PL 1. fig. 4). The structure of 

 these is explained under the head of PITTED 

 STRUCTURES. It must be understood, 

 however, that the peculiarity of Coniferous 

 wood does not depend on the presence of 

 these, which are common, but on the simul- 

 taneous absence of ducts. The wood of the 

 Yew presents in addition a spiral fibre, be- 

 tween the coils of which the pits lie. (See 

 TAXUS.) These peculiar conditions of the 

 wood render it possible to identify it in mi- 

 croscopic sections in a recent, and, if toler- 

 ably well preserved, even in a fossil state ; 

 the Coniferous structure may be readily de- 

 tected in silicified wood, in which almost all 

 trace of organic matter is lost, the silica 

 forming complete casts of the microscopic 



M 2 



