Spherical Embryo Research Articles

The Validity of the Spherical Cap Approximation in Heterogeneous Nucleation

Abstract On the basis of a general formulation of the Gibbs free energy change for heterogeneously nucleating systems, the difference in the free energy change for the formation of a spherical cap embryo and a sessile drop-shaped embryo is evaluated. This difference represents the error introduced by assuming the embryo is a spherical cap in the presence of a gravitational field. Power series expressions for the volume and surface areas of the sessile drop, based on the work of Bashforth and Adams, are used to arrive at the free energy change. Ratios allowing a comparison of the error for different systems are presented along with numerical values for a hypothetical, unit system. This hypothetical system is compared to water and to mercury with the result that the maximum relative error is 10−6. Based on this value, it is concluded that the spherical cap model is an adequate and useful approximation of the shape of an embryo in heterogeneous nucleation under the action of gravity.

The breeding and development of the ascidian Polycarpa tinctor

ABSTRACT The ascidian Polycarpa tinctor retains its embryos in the peribranchial cavities until they are advanced oozooids. Cleavage is total and leads to a spherical embryo with an outer’layer of ectoderm and a large central mass containing scattered endodermal and mesodermal cells. The gut first appears as a narrow space in the endoderm and differentiates as the embryo elongates. The first stage oozooid has 8 protostigmata and has the branchial and gut cavities filled with a non-cellular substance. This substance is absent in advanced embryos, which have 11 rows of definitive stigmata.

STUDIES OF THE DEVELOPMENT OF ZOSTERA MARINA L.: I. THE EMBRYO AND SEED

Development of Zostera marina L. is described from proembryo to mature seed. The single cotyledon and the stem apex develop laterally from the nearly spherical young embryo. No radicle is produced; the hypocotyl develops into a swollen basal part (the original embryonic mass) and an elongated axial part formed by cell divisions at the base of the cotyledon and plumule. The cotyledon grows in part by cell divisions at its apex. Curvature develops in the axial hypocotyl mainly by unequal elongation of cells, whereas curvature of the cotyledon is mainly by unequal increase in cell numbers. A single procambial strand differentiates from the suspensor end of the basal part of the hypocotyl through the axial part into the cotyledon and plumule. The plumular stem apex develops a single-layered tunica over a several-layered corpus. It produces three leaf primordia, one with air-spaces organized, before dormancy sets in. Mid-vein procambium differentiates acropetally from the axial strand into each leaf primordium; lateral procambial strands differentiate acropetally and basipetally from near the base in each of the first two primordia. Two adventitious root apices differentiate external to the axial procambium at the base of the cotyledon. Seed coat development is described briefly. The nucellus remains a non-vascularized column of cells extending upward from the highly vascularized attachment region of the seed. The patterns of development reported support the interpretation that the starchy, shield-shaped main part of the embryo is the basal part of the hypocotyl and that the first leaflike structure is the cotyledon.

Development of Seed of Linaria vulgaris

Previous articleNext article FreeDevelopment of Seed of Linaria vulgarisMelville T. CookMelville T. Cook Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 77, Number 2Apr., 1924 Article DOIhttps://doi.org/10.1086/333302 Views: 17Total views on this site Citations: 4Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:Travis L. Almquist, Katie L. Wirt, Jason W. Adams, Rodney G. Lym Adaptive Development of Yellow Toadflax ( Linaria vulgaris ) Chemical Control Recommendations, Invasive Plant Science and Management 8, no.33 (Jan 2017): 276–283.https://doi.org/10.1614/IPSM-D-14-00082.1Brij M. Johri, Kunda B. Ambegaokar, Prem S. Srivastava References, (Jan 1992): 1012–1073.https://doi.org/10.1007/978-3-642-76395-3_67Sophie Satina PERICLINAL CHIMERAS IN DATURA IN RELATION TO THE DEVELOPMENT AND STRUCTURE OF THE OVULE, American Journal of Botany 32, no.22 (Feb 1945): 72–81.https://doi.org/10.1002/j.1537-2197.1945.tb05089.xK. V. OSSIAN DAHLGREN DIE BEFRUCHTUNGSERSCHEINUNGEN DER ANGIOSPERMEN EINE MONOGRAPHISCHE ÜBERSICHT, Hereditas 10, no.1-21-2 (Jul 2010): 169–229.https://doi.org/10.1111/j.1601-5223.1927.tb02470.x

The Embryogeny of Some Cuban Nymphaeaceae

1. The development of the embryo sac is practically the same in all species. 2. In all species the endosperm nucleus divides and the daughter nucleus in the antipodal end enters a nucellar tube or sac which penetrates the nucellus. 3. This nucellar tube or sac is apparently for the purpose of transferring food from the nucellus to the endosperm, from which it is transferred to the embryo. 4. The endosperm is of two types: the cellular in Nymphaea and Castalia, and the nuclear followed by the cellular in Brasenia purpurea and Cabomba piauhiensis. 5. The character of the endosperm in the late stages of Brasenia purpurea and Cabomba piauhiensis indicates a greater importance in germination than in the other genera. 6. The embryo of Nymphaea advena(?) originates as a spherical mass of cells and later develops a cotyledonary ridge and suspensor, while the other species develop embryos consisting of a single row of cells, from which is formed a spherical embryo supported by a suspensor. A crescent-shaped cotyledonary ridge is then developed, ranging from two-thirds to almost the entire distance around the embryos. 7. With the development of the cotyledonary ridge, two cotyledonary lobes are produced which may readily be mistaken for two cotyledons.