The work opens with an exhaustive investigation into protozoa, exploring the fundamental functions of protoplasm, cell division, and the blurred boundaries between the animal and plant kingdoms. The author details the physiological reactions of amoeboid cells to environmental stimuli, setting a precise foundation for understanding cellular irritability, nutrition, and metabolism. Subsequent sections break down the taxonomy and anatomy of sarcodina, including detailed classifications of rhizopoda, foraminifera, heliozoa, and radiolaria, accompanied by structural analyses of their calcareous, arenaceous, and siliceous skeletons. The text transitions from unicellular organisms to the porifera, presenting a comprehensive examination of sponges.
It traces their internal canal systems, flagellated chambers, and spicule formation, illustrating how these multi-celled aquatic filter feeders operate without centralized organs or tissues. Further chapters systematically explore the coelenterata, ctenophora, and echinodermata, providing anatomical breakdowns of starfishes, sea-urchins, and sea-cucumbers. Throughout the text, the authors maintain a rigorous, observational approach to marine zoology, documenting reproductive cycles, multiple fission, syngamy, and embryonic development across various aquatic phyla. The concluding sections address historical debates on spontaneous generation and establish the specific constancy of species within classical marine biology.
