BOTRYDIUM. 



BOTRYLLOIDES. 



Fig. 75. 



Alga, 320, pi. 81. fig. 2 ; Kiitzing, Tab. Phyc. 

 pi. 10 ; Rabenhorst, Fl. Alg. ii. p. 37. 



BOTRYDTUM, Wallr. (Hydrogastrum, 

 Desv.). A genus of Siphonese (Confervoid 

 Algas), of which one species is found in 

 this country, growing upon damp, clayey 

 ground, the dried-up bottoms of ponds, &c. 

 A single plant, as developed from a spore or 

 gonidium, exhibits a remarkable character, 

 having a lower branched filamentous por- 

 tion, growing in the ground, and an erect 

 spherical or obovate portion, or head, about 

 the size of a mustard-seed, of a bright green 

 colour, the whole structure consisting 

 merely of a single cell, with one continuous 

 cavity running through the entire plant. 

 The figure (fig. 75) represents such a spe- 

 cimen, with a second 

 budding from it by ve- 

 getative increase ; and 

 in this way the plants 

 come to form tufts or 

 groups, like little bun- 

 ches of grapes ; hence 

 the name. The cell- 

 membrane acquires 

 considerable thickness ; 

 and at the period when 

 it is softening, and 

 about to dissolve to 

 allow of the escape of 

 the gonidia, it is seen 

 clearly to be composed 

 of numerous lamelte, 

 like that oi Hydrodic- 

 tyon. The globular head is lined, in the 

 full-grown specimens, with a layer of pro- 

 toplasm (primordial utricle), containing 

 abundance of chlorophyll-globules ; and at 

 a certain period breaks up into numerous 

 free globular asexual gonidia. 



When the air is dry, the protoplasm de- 

 scends into the branches, in little masses, 

 each forming a subterranean sporange, pro- 

 ducing zoospores; which are also some- 

 times formed in a vesicle springing above 

 ground, and capable of resisting desicca- 

 tion. 



Under the direct rays of the sun, the 

 head-protoplasm breaks up into cells, at 

 first green, then red. These, when free, 

 produce biciliated zoospores, which copu- 

 late. 



BIBL. Greville, Alffee Br. 196, pi. 19; 

 Hassall, Fr. Alga, 305, pi. 77. fig. 5 ; Kiit- 

 zing, Nova Acta, xix. pt, 2, pi. 69. figs. 1-10 ; 

 Braun, Verj. (Ray Soc. 1853) ; Itzigsohn, 

 Sot. Zeit. xiii. p. 257; Sachs, Bot. 275; 



Eostafinski & Woronin, Bot. Zeit. 1877 

 (Qu. Mic. Jn. 1878, xviii. 446). 



BOTRYL'LnLE. A family of Tunicate 

 Mollusca. Distinguished by the individual 

 bodies being united into a common mass, 

 which is attached ; and by the mantle being 

 united to the test at the orifices only. 



These animals form translucent gelatinous 

 or cartilaginous masses, of various hues of 

 orange, purple, yellow, blue, grey, and green ; 

 and are found under stones, or rocks, or in- 

 crusting sea- weeds, near low-water mark. 

 The bodies are often arranged in elegant 

 star-like clusters or systems ; the anal ori- 

 fices usually terminating in a common cen- 

 tral cavity or vent. Genera : 



Aptidium. Form variable; systems nu- 

 merous ; central cavity none ; bodies with 

 thorax, fore and hind abdomen ; branchial 

 orifice six-rayed; anal simple and indis- 

 tinct, 



Sidymim. Incrusting; systems conical, 

 truncate and starred at the summit, centre 

 depressed ; thorax and abdomen present ; 

 branchial orifice eight-rayed. 



Polyclinum. Form variable ; systems nu- 

 merous, convex and radiating, with cen- 

 tral cavity; bodies with thorax, fore ab- 

 domen, and long-stalked hind abdomen; 

 branchial orifice six- rayed; anal projecting 

 horizontally. 



Amaroucium. Lobed or incrusting, ses- 

 sile or stalked ; systems numerous, with a 

 central cavity ; bodies as in Aplidium. 



Leptoclinum. Thin, incrusting ; systems 

 numerous; bodies with thorax and ab- 

 domen; branchial orifice six-rayed; anal 

 opening into a common vent, more or less 

 branched. 



Distoma. Sessile; cartilaginous; form va- 

 riable ; systems numerous, circular ; bodies 

 in one or two rows at unequal distances 

 from a common centre, with thorax and 

 stalked abdomen; branchial and anal ori- 

 fices six-rayed. 



BotryUus. Incrusting, gelatinous; sys- 

 tems numerous ; bodies horizontal, in stars 

 round a common vent ; bodies undivided ; 

 branchial orifice simple, remote from the 

 vent. 



Botrylloides. As the last, but stars ir- 

 regular and ramifying; bodies vertical; 

 orifices approximated. 



Syntethys. Mass sessile, gelatinous, form- 

 ing a single system; bodies sessile; ori- 

 fices simple, without rays. 

 BIBL. See the Genera. 

 BOTRYLLOI'DES, M.-Edw. A genus 

 i2 



