Bancrofti is known to live in the lymphatic glands, and its embryos Microfilaria sanguinis hominis nocturna, passing by the thoracic duct, reach the blood-vessels and circulate in the blood.
Only the embryos of Leptodora are known to hatch out in the nauplius stage.
The embryos in the uterus are all nearly of the same age, except for a month or two before birth, when two broods overlap.
The worm inhabits the lung of the frog and toad, and is hermaphrodite (Schneider) or parthenogenetic (Leuckart); the embryos hatched from the eggs find their way through the lungs into the alimentary canal and thence to the exterior; in a few days they develop into a sexual larva, called a Rhabditiform larva, in which the sexes are distinct; the eggs remain within the uterus, and the young when hatched break through its walls and live free in the perivisceral cavity of the mother, devouring the organs of the body until only the outer cuticle is left; this eventually breaks and sets free the young, which are without teeth, and have therefore lost the typical Rhabditis form.
The eggs of the female give rise to embryos within the body of the mother; her other organs undergo a retrogressive change and serve as food for the young, until the body-wall only of the mother remains as a brown capsule.
41, B), where, however, the tentacles have quite disappeared, and the circular rim formed by the margin of the umbrella has nearly closed over the manubrium leaving only a small aperture through which the embryos emerge.
The sub-umbral cavity (s.c.) functions as a brood-space for the developing embryos, which are set free by rupture of the wall.
Medusae, so-called " meconidia," are budded but not liberated; each in turn, when it reaches sexual maturity, is protruded from the gonotheca by elongation of the stalk, and sets free the embryos, after which it withers and is replaced by another (Allman , p. 57, fig.
Nevertheless, though the conceptions originally denoted by " evolution " and " development " were shown to be untenable, the words retained their application to the process by which the embryos of living beings gradually make their appearance; and the terms" development," " Entwickelung,"and " evolutio " are now indiscriminately used for the series of genetic changes exhibited by living beings, by writers who would emphatically deny that " development " or " Entwickelung " or " evolutio," in the sense in which these words were usually employed by Bonnet or Haller, ever occurs.
The fertilized egg-cell (oospore) forms a filamentous structure, the proernbryo, from a restricted basal portion of which one or more embryos develop, one only as a rule reaching maturity.
The arrested embryos or eggs are then swallowed and digested by those in the same capsule which have advanced in development.
Rabl has with remarkable skill applied the method of sections to the study of the minute embryos of Planorbis.
Other Pulmonata possess, when embryos, Stiebel's canals in a more fully developed state, for instance, the common slug Limax.
Wheeler (1893) and others in various insect embryos, while in the lowest insect order - the Aptera - a pair of minute jaws - the maxillulae - in close association with the tongue are present, as has been shown by H.
No doubt can be entertained that the greater part of the inner layer corresponds to the mesoderm of more ordinary embryos, for the coelomic pouches, the germ-cells, the musculature and the vascular system all arise from it.
Wheeler (1889) on the embryos of two beetles - Hydrotails Lepisma and Machilis, an interesting transitional condition philus and Doryphora respectively.
Lecaillon (1898) on various leaf beetles, tend to show that the organ " in the embryos of the lower Arthropoda corresponds with whole of the " mid-gut " arises from the proliferation of cells at the the region invaginated to form the serosa of the hexapod embryo.
In the embryos of many insects there are projections from the segments of the abdomen similar, to a considerable extent, to the rudimentary thoracic legs.
In some embryos there is but a single pair of these rudiments (or vestiges) situate on the first abdominal segment, and in some cases they become invaginations of a glandular nature.
- Embryos of Springtail (Anurida maritima).
Occasionally the power of reproduction is thrown still farther back in the life-history, and it is found that from a single egg a large number of embryos may be formed.
Thus a mass or chain of embryos is produced, lying in a common cyst, and developing as their larval host develops.
In this way over a hundred embryos may result from a single egg.
If they fall on pasture land or fodder of any kind and are eaten by any herbivorous animal, such as a hare, rabbit, horse, sheep or ox, the active embryos or larvae are set free in the alimentary canal of the new host.
Here the eggs are fertilized and here they segment so that the young embryos are formed within their mother's 9 body.
The embryos escape into the uterus through the "bell," a funnellike opening continuous with the uterus.
M The "bell" swallows the matured embryos and passes them on into the uterus, and thus out of the body via the oviduct, which opens at one end into the uterus and at the other on to the exterior at the posterior end of o.-- the body.
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.
Von Baer in 1828, 5 Muller calls the attention of naturalists to the important fact, that while all the Squamata possess an amnion and an allantois, these structures are absent in the embryos of all the Nuda.
All segments passed should be burnt, and they should never be thrown where the embryos may become scattered.
In the case of filariasis due to Filaria bancrofti, which is common throughout the Tropics, the embryos of the parasite are disseminated by various Culicinae and Anophelinae (Culex pipiens in Queensland; C. fatigans in the West Indies; Myzomyia rossii in India; Pyretophorus costalis in a large portion of tropical Africa; &c.).
In diameter, with little yolk, and the embryos provided with large trophic vesicles (Willey).
In most of the African species, however, the embryos of the uterus are almost of the same age and are born at a definite season.
- A Series of Embryos of P. capensis.
The hind end of embryos B, C, D is uppermost in the figures, the primitive streak is the white patch behind the blastopore.
- A series of diagrams of transverse sections through Peripatus embryos to show the relations of the coelom at successive stages.
The following species are aberrant in respect of these characters: Peripatus (Opisthopatus) cinctipes, Purcell (Cape Colony and Natal), presents a few Australasian features; there is a small receptaculum seminis on each oviduct, some of the legs are provided with welldeveloped coxal organs, the feet have one anterior, one posterior and one dorsal papilla, and the successive difference in the ages of the embryos in the uterus, though nothing like that found in the neotropical species, is slightly greater than that found in other investigated African species.
The uterus appears to contain embryos of different ages.
Ova minute, with little food-yolk; embryos in the uterus at very different stages of development.
In these cocoons are deposited the eggs together with a certain amount of albumen upon which the developing embryos feed.
A highly specialized means of vegetative reproduction is seen in the tubers of Phylloglossum and the embryos of some Lycopods.
Some species of Botrychium have recently been found to have embryos provided with a suspensor.