LYSIGONIUM. 



[ 486 ] 



MACROSPORIUM. 



Braxton Hicks has stated that L. muralix, 

 a Sehiz'jgonium, and a Prasiola aro all dif- 

 ferent stages of the same organism, and has 

 noticed the segmentation of their gonidia 

 into Palmelloid cells. 



BIBL. Hassall, Brit. Fr. Alg. p. 219, 

 pis. 59, 60, 72; Harvey, Brit. Mar. Alg. 

 p. 225, pi. 26 E. ; Kiitz. Spec. Alg. p. 279 ; 

 Tab. Phyc. i. pi. 86-90 ; Rabenh. Fl. JBur. 

 Alg. ii. 135 ; B. Hicks, Qu. Mic. Jn. 1861. 



L YSIGO'NIUM. See MELOSIRA. 



M. 



MACERATION. The soaking of ob- 

 jects in various menstrua, for the purpose 

 of causing decomposition and solution of 

 portions of structure which are more readily 

 attacked, is an operation frequently had 

 recourse to in the anatomy both of animals 

 and plants. In addition to water, cold and 

 hot, a number of stronger agents are often 

 employed, chiefly oxidizing substances, such 

 as NITRIC ACID, the same combined with 

 chlorate of potash, &c. Ammonio-oxide of 

 copper dissolves delicate cellulose rapidly, 

 and does not so soon attack woody fibre, 

 &c. See TISSUES. 



MACHI'LIS, Latr. See PETROBIUS. 



MACROBIOTUS, Schultze. A genus 

 of Tardigrada (Arachnida), family Arctisca. 



Char. Head not furnished with append- 

 ages ; mouth terminated by a sucker, with- 

 out palps ; skin soft, with irregular rugae. 



M. Hufelandii (PI. 50. fig. 8). Body 

 cylindrical, colourless j head rounded in 

 front, with minute coloured eye-spots ; 

 sucker, pharyngeal tube, and styles well 

 developed; oesophageal bulb supported by 

 a solid frame- work of jointed pieces; legs 

 equal ; claws two, bifid, the point of each 

 again bifid; movement tolerably quick; 

 size 1-85 to 1-35". 



The most common species ; found upon 

 mosses growing on walls, stones, at the foot 

 of trees, &c. 



M. Oberhduseri. Dark brown; colour 

 distributed unsymmetrically in spots, and 

 forming five longitudinal bands ; no eye- 

 spots ; claws three, one simple, terminal, 

 and forming a short filament ; the two 

 others hooked, the interior one double or 

 bifid, the posterior simple ; movement very 

 active ; length 1-100 to 1-85". 



M. ursellus. Claws three, none fila- 

 mentous. 



M. Dujardinii. Claws two, bifid. 



BIBL. Doyere, Ann. Sc. Nat. 2 se*r. xiv., 

 xvii. and xviii. ; Dujardin, ibid. x. 



MACROCY'PRIS, Brady. An Ostra- 

 code, allied to Bairdia, among the Cypriiltr, 

 with long, smooth, pointed valves, and 

 characterized by short setae on the upper 

 antennae and rudimentary postabdominul 

 rami. Living in the North Sea (M. minna, 

 Baird); fossil in the Chalk (M. siltyua, 

 Jones). 



BIBL. G. S. Brady, Linn. Tr. xxvi. 391. 



MACROGONID1A. A name applied to 

 the larger form of ciliated zoospore found 

 in many Confervoid Algce, associated with 

 a form much smaller, distinguished as 

 MICROGONIDIA. See ZOOSPORES and HY- 



DRODICTYON. 



MACROSPORES, or MEGASPORES. 

 See SPORES. 



MAC'ROSPO'RIUM, Fr. A supposed 

 genus of Dematiei (Hyphomycetous Fungi J, 

 growing upon decaying vegetable matters, 

 corresponding to Septosporium, Corda, and 

 Helmisporium, Duby. Several species are 

 British. M. Cheiranthi, Fr., is common on 

 wallflowers and stocks j M. Brassicce, Berk., 

 on cabbage-leaves ; M. sarcinula, on gourds ; 

 and M. concinnum, on rotting decorticated 

 willow twigs. We have found one species 

 among the OIDIUM of the vine-fungus. 



Fig. 440. 



Macroaporium bulbotrichum. 

 Magnified 200 diams. 



Tulasne shows that they are conidiiferous 

 forms of a Sphaeriaceous genus. The spores 

 of different species of Macrosporium were a 

 very prominent feature in the organisms 

 observed in deposits from the air at Cal- 

 cutta. 



BIBL. Berk. Br. FL ii. pt. 2. 339 ; Ann. 

 N. H. i. 261, pi. 8. fig. 10, vi. 435, pi. 12. 

 fig. 21; Fries, Summa Veget. 501; Si/st. 

 Mi/col, iii. 274 ; Corda, Ic. Fung. i. 175, 

 176, 188; Tulasne, Ann. Sc. Nat. 4 ser. 



