Note 145 — Chapter VII · THE ELEMENTARY STRUCTURE OF THE NERVOUS SYSTEM.

Auerbach (Ueber einen Plexus Myentericus, 1862) describes the ganglia as filled with apolar cells, among which only a few are unipolar. Stieda (Centralnervensystem der Vögel, 1868) finds both apolar and unipolar cells in the spinal ganglia of birds. Axmann (De Gangliorum Systematis Structura penitiori, 1847) says the spinal cells are all unipolar. Schwalbe (Archiv für mikros. Anat., 1868) and Courvoisier (ibid., 1869) say the same. So also Ranvier, Comptes Rendus, 1875. Kölliker (Gewebelehre) speaks decidedly in favor of both apolar and unipolar cells, but thinks the apolar are embryonic. Pagliani (Saggio sullo Stato attuale delle Cognizioni della Fisiologia intorno al Sistema nervoso, 1873), who represents the views of Moleschott, admits the existence of apolar and unipolar cells. The authors just cited are those I happen to have before me during the rewriting of this chapter, and the list might easily be extended if needful. Auerbach, Bidder, and Schweigger-Seidel describe unipolar cells which in some places present the aspect of bipolar cells simply because two cells lie together, their single poles having opposite directions. I will add that the bipolar cells do not really render the physiological interpretation a whit more easy than the unipolar, for they are simply cells which form enlargements in the course of the nerve-fibres.