The embryo generally fills the seed, and the cotyledons are rolled or folded on each other.
If the egg with its contained embryo falls into water E (All from Marshall and Hurst, after Thomas.) FIG.
When the young sporophyte first begins its independent lifewhen, that is, it exists in the form of the embryo in the seedits living substance has no power of utilizing the simple inorganic compounds spoken of.
The germ band evidently marks the ventral aspect of the developing insect, whose body must be completed by the extension of the embryo so as to enclose the yolk dorsally.
Folsom has detected in the embryo of Anurida a pair of ganglia (fig.
The embryo of Gnetum forms an out-growth from the hypocotyl, which serves as a feeder and draws nourishment from the prothallus.
Both nuclei are elongated vermiform structures, and as they enter the embryo sac present a twisted appearance like a spermatozoid without cilia (fig.
Chun and Woltereck, on the other hand, regard the stem as a stolo prolifer arising from the aboral pole, that is to say, from the ex-umbrella, similar to that which grows out from the ex-umbral surface of the embryo of the Narcomedusae and produces buds, a view which is certainly supported by the embryological evidence to be adduced shortly.
It has been ascertained that the nephridia of Oligochaeta are preceded in the embryo by a pair of delicate and sinuous tubes, also found in the Hirudinea and Polychaeta, which are larval excretory organs.
The embryo is provided with ten hooks, and appears to select Lamellibranchs (Mactra) for its intermediate host.