The development of the human body; a manual of human embryology . ich areaggregates of organs havingcorrelated functions. It is the province of embry-ology to study the mode of di-vision of the fertilized ovumand the progressive differenti-ation of the resulting cells toform the tissues, organs, andsystems. But before consider-ing these phenomena as seenin the human body it will be well to get some generalidea of the structure of an animal cell. This (Fig. 1), as has been already stated, is a mass ofprotoplasm, a substance which in the living condition is aviscous fluid resembling in many of i
The development of the human body; a manual of human embryology . ich areaggregates of organs havingcorrelated functions. It is the province of embry-ology to study the mode of di-vision of the fertilized ovumand the progressive differenti-ation of the resulting cells toform the tissues, organs, andsystems. But before consider-ing these phenomena as seenin the human body it will be well to get some generalidea of the structure of an animal cell. This (Fig. 1), as has been already stated, is a mass ofprotoplasm, a substance which in the living condition is aviscous fluid resembling in many of its peculiarities egg-albumen, and like this being coagulated when heated orwhen exposed to the action of various chemical to the structure of living protoplasm little is yet known,since the application of the reagents necessary for its accu-rate study and analysis results in its disintegration orcoagulation. But even in the living cell it can beseen that the protoplasm is not a simple homogeneoussubstance. What is termed a nucleus is usually clearly. Fig. 1.—Ovum of New-bornChild with Follicle-cells.—(Mertens.) 2d THE DEVELOPMENT OF THE HUMAN BODY. discernible as a more or less spherical body of a greaterrefractive index than the surrounding protoplasm, andsince this is a permanent organ of the cell it is con-venient to distinguish the surrounding protoplasm as thecytoplasm from the nuclear protoplasm or karyoplasm. The study of protoplasm coagulated by reagents seemsto indicate that it is a mixture of substances rather thana simple chemical compound. Both the cytoplasm andthe karyoplasm consist of a more solid substance, thereticulum, which forms a network or felt-work, in theinterstices of which is a more fluid material, the enchy-lema* The karyoplasm, in addition, has scatteredalong the fibers of its reticulum a peculiar materialtermed chromatin and usually contains embedded in itssubstance one or more spherical bodies termed nucleoli,which may be simply larg
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
