History of infusoria, including the desmidiaceae and diatomaceae, British and foreign / by Andrew Pritchard.

  • Andrew Pritchard
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: History of infusoria, including the desmidiaceae and diatomaceae, British and foreign / by Andrew Pritchard. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    710 SYSTEMATIC HISTOKY OF THE INFUSOllIA. rical, reaching 1-50' in length and 1-07' | 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 grey of the female ova. The former likewise contam fewer granules. The development by hssion similar in both. When the egg is mature, it continues to be pale and transparent. The red eye-speck exhibits itself; but the maxillary apparatus, seen in the female ovimi, is wanting. On the other hand, two or three heaps of dark gramdes occur, not seen in the females. The embryo escapes from the_ ovum by a transverse raptm-e, and is then seen to have a diflerent contom- 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 tubidar foot about one-fifth the length of the body. Head crowned by a flat- tened disc, with a wide expanding mar- gin, clothed with long vibrating cilia and a few non-vibratile 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 pyri- form vesicvdar testicle, 1-100' in length, occupies the middle of the body; it is fiUed with small dark moving sjjerma- tozoa. The wall of the testicle is very thick, and elongated at its upper extre- mity into a thick cylindrical band, which is attached to the cephalic disc. Pos- teriorly the testicle is striated longitu- dinally, and is perforated by an apertm-e 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 furnished with vibratile cilia. The Ibot is transversely ^^Tinkled, and ends in two small toes. Near the root of the penis are two club-shaped glands which pour their secretion into its cannl; 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,—llie larger of these, the supposed cerebral ganglion, supporting the eye-spot. Two or three vesicles of uncertain character, filled with dark gi-anules, 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 bracldsh waters. Length of females from 1-96 to 1-72. (xxxix. 10-20; XL. 20-23.) B. ruhens (JB. urceolaris, M.).—Lorica smooth, with six shai-p spines in front, posteriorly rounded; the body is red. 1-50. Dajardin supposes this to be a variety of B. urceolaris. Leydig recog- nizes its distinctness, (xxxvin. 7.) B. Mnllori (Iliiller's Brachionus). — Lorica smooth, with six obtuse spines in fr-ont, two short ones behind, resembling papillse. This species is somewhat larger than B. urceolaris, and has peculiarly- shaped fr'ontal spines. The margin of the chin (brow) is smoothly trunca,te, ■with three faint indentations. The lorica is very transparent. 1-60. According to Mr. Gosse* the B. hqitatomus found in sea-water is identical with this species. (xxxix. 13.) B. hrevispinm.—Lorica smooth, having six acute imequal 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 riuming clear water, ■s\'ith Con- fei-va3. 1-65. B. Bakei-i (]\L).—Lorica rough, its middle tessellated on the dorsal smface; six imequal acute teeth anteriorlj^, two elongated (lateral and dorsal) spmes posteriorly, and short ones at the sheath of the foot. The lorica is covered with delicate gramdes; those upon the middle of the venti-al sm-face ai-e an-auged m pai-allel but somewhat ciu-ved lines. 1-220 to 1-60. (xxx-sTn. 8, 9, 10-17; XL. 16.) The following interesting observa- tions as to the development of this spe- cies have been communicated to me by a friend, an accurate and diligent obseiTer of nature:—About two o'clock B. Ba- heri was observed Avith one egg placed externallv between the two posterior spines of the shell, and another small eog in the left side of the animal, which increased much in size in the coiu-se 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 tlio young Brachionus