710 



SYSTEMATIC HISTOEY OF THE INFUSORIA. 



rical, reacliing 1-50'" in lenoili and 1-67'" 

 in diameter. Their shell is more deli- 

 cate and the contents clearer and more 

 transparent, as well as of a pale yellowish 

 hue instead of the dusky gTey of the 

 female ova. The former likewise contain 

 fewer gTanules. The development by 

 fission similar in both. When the egg- 

 is mature, it continues to be pale and 

 transparent. The red eye-speck exhibits 

 itself 5 but the maxillary apparatus, seen 

 in the female ovum, is wanting. On the 

 other hand, two or three heaps of dark 

 gi-anides occur, not seen in the females. 

 The embryo escapes from the ovum 

 by a transverse rupture, and is then 

 seen to have a different contoiu* from 

 the female. It is but one-third the 

 size of the latter, being, when extended, 

 but 1-27'" to 1-22'" long, and from 

 1-60"' to 1-55'" broad. It is destitute 

 of a firm lorica -, short, cylindrical ; pro- 

 longed anteriorly into a short head, 

 separated by a constriction from the 

 trunk ; prolonged posteriorly into a short 

 tubular foot about one-fifth the length 

 of the body. Head crowned by a flat- 

 tened disc, with a wide expanding mar- 

 gin, clothed mth long vibrating cilia 

 and a few non-^dbratile bristles. Cilia 

 moving with extraordinary velocity'-, pre- 

 venting many being seen at once ; but a 

 little strychnine added to the water 

 checks their action and facilitates their 

 observation. No mouth is present; hence 

 the ciliary wreath is not twined inwards 

 at the oral fissm-e ; the alimentary appa- 

 ratus is wholly wanting. A large pp'i- 

 fonn vesicular testicle, 1-100'" in length, 

 occupies the middle of the body ; it is 

 filled with small dark moving sperma- 

 tozoa. The wall of the testicle is very 

 thick, and elongated at its upper extre- 

 mity into a thick cylindi'ical band, which 

 is attached to the cephalic disc. Pos- 

 teriorly the testicle is sti'iated longitu- 

 dinally, and is perforated by an aperture 

 opening into a wide spermatic duct con- 

 ducting to the penis. The latter organ 

 is a short tube usually laid free on the 

 foot and nearly extending to its extre- 

 mity ; its internal canal and outer mar- 

 gin equally fiu-uished with vibratile cilia. 

 The foot is transversely wrinkled, and 

 ends in two small toes. Near the root 

 of the penis are two club-shaped glands 

 which pour their secretion into its canal ; 

 near these is also a contractile vesicle 

 with two water-canals and their ap- 

 pended tags. Several spherical cell-like 

 bodies occur near the head, — the larger 

 of these, the supposed cerebral ganglion, 



supporting the eye-spot. Two or three 

 vesicles of imcertain character, filled 

 Tvith dark granules, rest on the testicle 

 near its lower end. The males are much 

 rarer than the females, and are not seen 

 after the end of May. In fresh and 

 brackish waters. Length of females 

 from 1-96" to 1-72". (xxxix. 10-20; 

 XL. 20-23.) 



B. rubens (JB. urceolaris, M.). — Lorica 

 smooth, with six sharp spines in front, 

 posteriorly roimded; the body is red. 

 1-50". Diijardin supposes this to be a 

 variety of B. urceoJaris. Ley dig recog- 

 nizes its distinctness, (xxxvni. 7.) 



B. Iliillen {Miiller^s Urachionus). — 

 Lorica smooth, with six obtuse spines in 

 fi'ont, two short ones behind, resembling 

 papillae. This species is somewhat larger 

 than B. urceolaris, and has peculiarly- 

 shaped frontal spines. The margin of 

 the chin (brow) is smoothly truncate, 

 with three faint indentations. The lorica 

 is very transparent. 1-60". According 

 to Mr. Gosse, the B. hq)tatomus found in 

 sea-water is identical with this species. 

 (xxxix. 13.) 



B. hrevisphuis. — Lorica smooth, having 

 six acute unequal spines in fi'ont, and 

 four stout spines posteriorly, the two 

 inner ones short ; two sexual glands and 

 a contractile vesicle are present. In 

 slow running clear water, with Con- 

 fen^se. 1-65". 



B. Bakeri (M.). — Lorica rough, its 

 middle tessellated on the dorsal smface ; 

 six unequal acute teeth anteriorly, two 

 elongated (lateral and dorsal) spines 

 posteriorly, and short ones at the sheath 

 of the foot. The lorica is covered with 

 delicate granules ; those upon the middle 

 of the ventral surface are aiTanged in 

 parallel but somewhat curved lines. 

 1-220" to 1-60". (xxxvm. 8, 9, 10-17 ; 

 XL. 16.) 



"The following interesting observa- 

 tions as to the development of this spe- 

 cies have been commimicated to me by a 

 friend, an accurate and diligent observer 

 of natui'e : — About two o'clock B. Ba- 

 keri was observed with one egg placed 

 externally between the two posterior 

 spines of the shell, and another small 

 egg in the left side of the animal, which 

 increased much in size in the course of 

 the day. At nine in the evening_ a 

 motion was perceived in the exterior 

 egg like that of the muscular oesophagus 

 of the parent; and about this time the 

 internal egg was protruded and placed 

 by the side of the other, being longer 

 than it. At eleven the young Brachionus 



