CONIOPHYTUM. 



[ 204 ] 



CONJUGATION. 



London Journ. of Bot. iii. 320 ; Tulasne, 

 Compt. Rendus, March 1851 (Ann. N. H. 

 1851, viii. 114) ; Ann. Sc. Nat. 3 se*r. xv. 

 370, xx. 129, 4 s<$r. ii. 77, v. p. 108; Botan. 

 Zeit. xi. 49; Compt. Rend. 1854 (Ann. N. 

 H. 2 ser. 1854, 76) ; Fries, Syst. Mycol ; 

 De Bary, Brand-Pilze, Berlin, 1853. 



CONIO'PHYTUM, HassaU (Dolicho- 

 spermutn, Ralfs). A genus of Nostocha- 

 ceae (Confervoid Algae), consisting of one 

 species ; colouring large sheets of water of 

 a deep coppery green, by its minute fronds, 

 each composed of a number of filaments 

 variously curled and interwoven, densely in 

 the centre, and more loosely towards the 

 circumference ; these fronds being free, look 

 like a pulverulent or granular accumulate >n 

 in the water, when viewed by the naked J 

 eye. The genus differs from its allies in 

 the relative positions of the spermatic and 

 vesicular cells, the former being either ! 

 next to, or at a distance from the latter. 

 This fact seems to throw some doubt on 

 the value of this character as a distinctive 

 mark. 



C. Thompsoni, Ralfs (PI. 3. fig. 9), = Do- 

 lichospermum Thomp., Ralfs, Ann. N. H. 

 1850, v. 336, pi. 9. fig. 3. Anabaina Flos- 

 aqua, Harvey, Brit. Alga, ed. 1 ; Hassall, 

 Alga, pi. 75. f. 2; also Bot. Gaz. 1850 

 (Colour of the Serpentine). 



CONIOTHE'CIUM, Corda. An obscure 

 genus of Torulacei (Coniomycetous Fungi) ; 

 the so-called species being probably forms 

 of some other Fungi. 



C. amentacearum is extremely common 

 on dead willow-twigs. 



BIBL. Berk, and Broome, Ann. N. H. 

 1850, v. 460 ; Corda, Ic. Fung. i. figs. 21, 

 25, 26 ; Fries, Summa Veget. 523. 



CONIOTHY'RIUM, Corda. A genus of 

 Sphaeronemei (Stylosporous Fungi). 



C. glomeratum, Corda, recorded by Berke- 

 ley and Broome as Biitish, is said by Fries 

 to belong to his genus Clisosporum. It is a 

 microscopic plant growing in the cracks of 

 dead wood (elm) ; composed of minute free 

 membranous peridia enclosing numerous 

 spores, which escape by the bursting of the 

 apex. 



BIBL. Berk, and Broome, Ann. N. H. 

 1854, xiii. 400; .Corda, iv. f. 208; Fries, 

 Summa Veget. 522 ; Montague, Ann. Sc. 

 Nat. 8 ser. xii. 304. 



CONJUGATION or ZYGO'SIS. A 

 process occurring among many of the lower 

 plants and animals, in which the substance 

 of two distinct organisms comes into con- 



Fig. 137. 



tact and becomes fused into a single mass, or 

 zygospore. This operation is always con- 

 nected with reproduction in plants, some- 

 times also in animals. 



In the vegetable kingdom it has been ob- 

 served in the Algae, viz. in the Zygnemaceae, 

 the Desmidiaceae, the Diatomaceae, the Pal- 

 mellaceae, and in the genus Syzygites of 

 Fungi ; also in the Myxomycetes. It also 

 occurs in the zoospores. In all these cases 

 it consists essentially in the blending to- 

 gether of the contents of two distinct cells : 

 either by the complete fusion of two free 

 cells; by the passage of the contents of 

 one cell into the cavity of another through 

 newly-formed connecting tubes ; or by the 

 emission of the contents of both cells into 

 a space between them, where the mixed 

 contents become enclosed in a special en- 

 velope. 



The conjugation ear- 

 liest discovered was that 

 of the Zygnemaceae, in 

 which the cells of dis- 

 tinct filaments lying pa- 

 rallel with one another, 

 become united by late- 

 ral inosculation or by 

 cross branches, formed 

 by the budding out of 

 the walls of the cells 

 opposite to each other, 

 the protruded processes 

 coming into contact, co- 

 hering and becoming 

 confluent by the absorp- 

 tion of the surfaces of 

 contact (fig. 137). The 

 cavities of the two cells being thus freely 

 opened into one another, the contents be- 

 come mixed ; in Spiro- 

 gyra and Zygnema the 

 contents of one of the 

 cells usually travel 

 across into the cavity of 

 the other (PI. 9. fig. 18); 

 in Zygogonium the con- 

 tents of both cells collect 

 in the cross-piece, this 

 is the case also in Meso- 

 carpm (fig. 138) and 

 Staurocarpus, in the lat- 

 ter of which the cross- 

 piece becomes greatly 

 enlarged. The contents 



in all these Cases be- Conjugating filaments 



come retracted from the 

 cell-wall, and, secreting 



Zygnema cruciata. 

 Conjugating filaments. 

 Magnified 250 dia- 

 meters. 



Fig. 138. 



Mesocarpus acalaris. 



with spores. 

 Magnified 200 dia- 



