Many Gastropoda deposit their eggs, after fertilization, enclosed in capsules; others, as Paludina, are viviparous; others, again, as the Zygobranchia, agree with the Lamellibranch Conchifera (the bivalves) in having simple exits for the ova without glandular walls, and therefore discharge their eggs unenclosed in capsules freely into the sea-water; such unencapsuled eggs are merely enclosed each in its own delicate chorion.
From these masses of ova dehisce into the body cavity and float in its fluid.
The developing ova are 19.
To establish the exact relationship it is necessary not only to breed but to rear the medusa, which cannot always be done in 1 In some cases hydroids have been reared in aquaria from ova of medusae, but these hydroids have not yet been found in the sea (Browne [Io a]).
Ov, Ova, two carried on each female gonophore..
To get at the female and the ova prolonged soaking in soap and water is necessary, the epiderm being rubbed away and the ointment then applied.
The fundamental uniform fact in nature is constant change (lravra Xwpei Kai ovSiv Ova); everything both is and is not at the same time.
The ova of Anopheles are tiny black rodshaped objects, which are deposited on the water of natural puddles, ponds, or slowly moving streams, by preference those which are well supplied with vegetation; they float, singly or attached to other objects or clustered together in patterns.
The ova of Culex, on the other hand, are deposited in any stagnant water, including cesspools, drains, cisterns, or water collected in any vessel; they float in boat-shaped masses on the surface.
Of the Physostomi, the siluroids are abundant in the estuaries and muddy waters; the habits of some of these fishes are remarkable, such as that of the males carrying the ova in their mouths till the young are hatched.
There is no possibility that sperm and ova can escape by these tubes not in company with coelomic fluid.
They contrast with those of the Oligochaeta and Hirudinea by reason of their frequently close association with the gonads, the same organ sometimes serving the two functions of excretion and conveyance of the ova and spermatozoa out of the body.
In some Syllids, such as Pionosyllis gestans, the ova are attached to the body A FIG.
Special sacs developed from the intersegmental septa lodge the developing ova and sperm.
No separate spermathecae or septal chambers for the development of the ova and sperm.
2; in addition, cn, nerve cord; in, intestine; nf, parts of nephridium; on, external opening of nephridium; ov, ova; 1, testis.
Males in nearly all species appear once a year, when the last female generation, the ovigerous generation, is fertilized, and a few large ova are produced to carry on the continuity of the species over the winter.
A series 750.) I, The longitudinal of sacs lined with an epithelium, the proexcretory canal; 2, one liferation of which gives rise to the ova of the tags containing the or spermatozoa, alternate between the flame-cells.
The ova and Zool.
As the ova are in many species deposited in a gelatinous tube secreted by the bodywalls, in which they are arranged (three or more together) in flaskshaped cavities, impregnation must probably take place either before or at the very moment of their being deposited.
But should the "bell" swallow any of the ova, or even one of the younger embryos, these are passed back into the body cavity through the second and dorsal opening.
The development of Balanoglossus takes place according to two different schemes, known as direct and indirect, correlated with the occurrence in the group of two kinds of ova, large and small.
Cells which line it to the ova and spermatoza, it is of the nature of a true coelom.
The ova and the spermatozoa 4.
In subsequent generations produced by self-fertilization of the hybrids it was found that the positive character was not present in all the individuals, but that a result was obtained showing that in the formation of the reproductive cells (ova and sperms) of the hybrid, half were endowed with the positive character and half with the negative.
The cod spawns in February, and is exceedingly prolific, the roe of a single female having been known to contain upwards of eight millions of ova, and to form more than half the weight of the entire fish.
B, Udonella caligorum, attached to the ova of the copepod Caligus.
The fertilized ova, provided with yolk and a shell, are next transferred to the "uterus" along which they travel to the exterior.
In these, the male organs ripen before the ova and spermatozoa may pass into the uterus before the external pore is formed (Looss).
Some authors looking upon these as parthenogenetic ova regard the developmental cycle as one composed of an alternation of parthenogenetic and of sexual generations.
Buonanni, a learned Jesuit of Rome) that they are not generated out of the mud or sand found on the seashore or the beds of rivers at low water, but from spawn, by the regular course of generation; and he maintained the same to be true of the fresh-water mussel (Unio), whose ova he examined so carefully that he saw in them the rotation of the embryo, a phenomenon supposed to have been first discovered long afterwards.
The small ova are crowded beneath the dorsal part of the valves.
Ova in single or double or rarely several 4 FIG.
The Trypanosomes ultimately overrun practically all parts of the body, sometimes not even the ova escaping.
Angulata) have the sexes separate, and fertilization is effected in the open water after the discharge of the ova and the spermatozoa from the females and males respectively.
But the generative products do not pass through the whole length of the renal tube: there is a direct opening from the pericardial end of the tube to the distal end, and the ova or sperms pass through this.
In Yoldia and Nucula proxima the ova are set free in the water and the test-larvae are free-swimming, but in Nucula delphinodonta the female forms a thin-walled egg-case of mucus attached to the posterior end of the shell and in communication with the pallial chamber; in this case the eggs develop and the test-larva is enclosed.
The Fallopian tubes receive the ova and carry them to the uterus.
The coelom opens to the exterior by ducts which are primarily genital ducts by which the ova or sperms are discharged.
As a rule no parental care is exhibited, but incubation of the developing ova within some part of the parental body, or receptacles attached to the parent, occurs in some Lamellibranchs, some Gastropods, and in Argonauta among the Cephalopods.
True viviparity, that is the development of the ova within the oviduct, is very rare, occurring only in one case among the Amphineura and in some aquatic and pulmonate Gastropoda.
Hence, when he returns to organisms, it does not surprise us that he assigns to ova and spermatozoa cell-souls, to the impregnated ovum germ-soul, to plants tissue-souls, to animals nerve-souls; or that he regards man's body and soul as born together in the impregnated ovum, and gradually evolved from the bodies and souls of lower animals.
A number of ova ripen simultaneously.
The eggs may be laid separately invested by a chitinous envelope, or as in Ischnochiton magdalenensis they may form strings containing nearly 200,000 eggs, or the ova may be retained in the pallial groove and undergo development there, as in Chiton polii and Hemiarthrum setulosum.
One species Callistochiton viviparus is viviparous and its ova develop without a larval stage in the maternal oviduct.
Ova are developed on the median, spermatozoa on the outer wall of each genital tube.
Sipunculoids are dioecious, and the ova and spermatozoa are formed from the modified cells lining the body-cavity, which are heaped up into a low ridge running along the line of origin of the retractor muscles.
The ova and the mother-cells of the spermatozoa.
From Serai Keui); (7) Colossae (near Chonas); (8) Ceretapa Diocaesarea (Kayadibi); (9) Themisonium (Karayuk Bazar); (IO) Tacina (Yarishli); (II) Sanaus (Sari Ka y ak, in Daz Kiri); (12) Dionysopolis (Orta Keui); (13) Anastasiopolis, originally a village of the Hyrgaleis (Utch Kuyular); (14) Attanassus (Eski Aidan); (15) Lunda (Eski Seid); (16) Peltae (Karayashlar); (17) Eumenea (Ishekli); 08) Siblia (Homa); (19) Pepuza (Duman or Suretli); (20) Bria (Bourgas); (21) Sebaste (Sivasli); (22) Eluza or Aludda (Hadj imlar); (23) Acmonia (Ahat Keui); (24) Alia (Kirka); (25) Siocharax (Otourak), (26) Dioclea (Dola); (27) Aristium (Karaj Euren, in Sitchanli Ova); (28) Cidyessus (Geukche Eyuk); (29) Apia (Abia); (30) Cotyaeum (Kutaiah); (31) Aezani (Tchavdir Hissar); (32) Tiberiopolis (Amed); (33) Cadoi (Gediz); (34) Ancyra (Kilisse Keui) (35) Synaus (Simav); (36) Flaviopolis Temenothyrae (Ushak); (37) Trajanopolis Grimenothyrae (Giaour Euren, near Orta Keui); (38) Blaundus (Suleimanli).
(3) The rest of Phrygia is mountainous (except the great plateau, Banaz Ova), consisting of hill-country intersected by rivers, each of which flows through a fertile valley of varying breadth.
Great part of southern and western Phrygia is drained by the Maeander with its tributaries, Sandykly Tchai (Glaucus), Banaz Tchai, Kopli Su (Hippurius), and Tchuruk Su (Lycus); moreover, some upland plains on the south, especially the Dombai Ova (Aulocra), communicate by underground channels with the IVlaeander.
3 Trees are exceedingly scarce in the country; and the pine-woods on the western tributaries of the Sangarius and the valonia oaks in parts of the Banaz Ova and a few other districts form exceptions.
The researches of Hoek have shown that in the same oyster the genital organs at one time produce ova, at another spermatozoa, and that consequently the oyster does not fertilize itself.
The ova are fertilized in the genital duct, and before their escape have undergone the earliest stages of segmentation.
The whole tree itself is but one leaf, and rivers are still vaster leaves whose pulp is intervening earth, and towns and cities are the ova of insects in their axils.
Ova large and with much yolk.
Finally, the Karayuk Ova in the extreme southwest drains through the Kazanes, a tributary of the Indus, to the Lycian Sea.