All stages of Ceratozetes cisalpinus Berlese were sectioned successfully. Fixation in a modified Bouin's solution (with tetrahydrofuran substituted for the alcohol), with immediate puncturing, and embedding with a Tissuemat-N-butyl metacrylate provided excellent, undistorted sections of the heavily sclerotized adults; Tissuemat alone was sufficient for the immature stages. The molting process is divisible into a premolt and a hardening period, and one type of endocrine glands fluctuates in size, shape, and structure with the molting period. Except for the single pair of podosomatal glands, the smaller, more numerous dermal glands in immature stages are not the precursors of adult dermal glands; all dermal glands are associated with porose areas. The dorsal-opistosomatal gland (latero-abdominal of Grandjean) is poorly developed in this species. Salivary glands are formed from epidermal cells and are present only in adults. The epidermis disappears after adult sclerotization is complete. A central suspensory ligament forms a stable framework for muscle attachment in the region of the brain. The brain gives off 14 nerves, plus the ventral trunk. All tracheae originate from acetabula I and III, and each ends as a slightly swollen bulb. The digestive system comprises a stomodeum, a mesenteron, and a proctodeum; during molting a plug forms to block off each end of the mesenteron while the cuticular linings of the other two sections are replaced. The proventricular glands were found to contain green granules. Food flow is accomplished only by body-fluid hydraulic pressure and by further ingestion of food. The supracoxal gland is regarded as possibly being an excretory organ. The female matures up to 18 eggs at one time and deposits them simultaneously; the ovipositor is extruded by body-fluid pressure and retracted by special muscles. The penis is not an intromittent organ, but with the stalk-gland secretion forms the spermatophore.