DER BULBUS OLFACTORIUS ACCESSORIUS BEI INSEKTIVOREN UND PRIMATEN

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Abstract
The olfactory bulb was investigated in 48 insectivores and primate species, namely in 8 "basal" insectivores, 11 "progressive" insectivoree, 12 prosimians and 17 simians = anthropoids. In all insectivores and prosimians an accessory bulb was distinctly formed; among the simians it was present in all the platyrrhini (new-world monkeys), however, in no catarrhini (old-world monkeys). In all of the "basal" insectivores the accessory bulb is well developed, but Its relative size when compared to the neighboring main bulb is small Contrary to what former authors have asserted, it is not rudimentary. The size of the accessory bulb varies considerably among the "progressive" insectivores (it is large in Elephantulus, Neomys, Nesogale and Talpa, small in Desmana, Rhynchocyon andTEalemys). It gives the impression of being large in Potamogale because in this animal the main bulb is greatly reduced in all insectivores (basal and progressive) the vomeronasal nerve approaches the accessory bulb medially while the latter can be considered as lying medial to a sagittal plane dividing the ventricle in halves. In all prosimians (except Tupaia and probably Lemur of which only a horizontal section was available for examination) the adjacent bulb lies lateral to this sagittal plane and the vomeronasal nerves approach it in general laterally. The accessory bulbs are always well developed and only in Tarsius somewhat smaller. The accessory bulb is well developed in Platyrrhini, medially situated with the vomeronasal nerve approaching it medially. Aotes is an exception inasmuch as the accessory bulb is very small and dorso-latirally situated. When the accessory bulb is small, the cell layers merge and the inner granules are definitely scantier. These changes are identical with those found in reduced main bulbs (as in man). Investigations confirm earlier findings in which it was shown that main bulb and accessory bulb are independent of one another as regards size.