feb. 1899] FRESH FACTS 151 



has defined a brain as the general motor centre associated with at least one of 

 the higher sensory nerves. In this sense there is a brain in the supra- 

 oesophageal ganglia of Crustacea and Tracheata, but not in Molluscs, Annelids, 

 Nemertines, or Planarians, not to speak of Echinoderraa and Coelentera. In 

 the dorsal ganglion of Octopus there seems to be a cerebrum in the Vertebrate 

 sense, but not a real " brain." 



Evolution of the Brain. B. Haller. — " Vom Bau des Wirbelthiergehirns," 

 I. Theil, Salmo und Scyllium (Morphol. Jahrb., 1898, xxvi. pp. 345-641, 11 pis. 

 and 23 figs.) As a speculative conclusion based on a multitude of facts, Haller 

 suggests that the ancestor of the Chordata (the Helminth, to wit) had for its 

 central nervous system a pair of supra-oesophageal ganglia and lateral nerve 

 cords. The latter approached dorsally and coalesced in a single cord, whose 

 central canal remains as a sign of the primitive separateness. The canal was 

 continued forward to the primitive brain, probably the region of the ganglia 

 habenulae, where a similar cavity arose by a fusion of the ventral parts of the 

 ganglia. Thereafter followed a metameric differentiation of the nerves, both 

 cranial and spinal, while the formation of the Vertebrate eyes and the concen- 

 tration of the olfactory spheres gave an early impulse to anterior cerebral 

 differentiation. 



Changes in the Dendrites. S. Soukhanoff. — "Contribution a l'etude 

 des modifications que subissent les prolongements dendritiques des cellules 

 nerveuses sous l'influence des narcotiques " (La Cellule, 1898, xiv. pp. 387-395 

 1 fig.) " L'anatomie pathologique de la cellule nerveuse en rapport avec l'atrophie 

 variqueuse des dendrites de l'ecorce cerebrale " (T. C, pp. 399-415, 4 figs.) In 

 the guinea-pig intoxicated with trional, poisoned with arsenic, subjected to 

 thyroidectomy, or otherwise treated so as to bring about marked nutritive 

 disturbances, the dendritic prolongations in the cells of the cerebral cortex 

 become markedly moniliform or varicose, which probably implies a degenerative 

 process associated with relative atrophy. The particular interest of this is, 

 that traces of the moniliform state are to be seen in the normal condition. 



The Lens of the Mole's Eye. C. Ritter. — " Die Linse des Maulwurfes " 

 (Arch, f. mikr. Anat., 1898, liii. pp. 397-403, 3 figs.). The minute lens is 

 without a nucleus and without concentric structure, in fact, rather like a half- 

 made lens in the frog. It permits the passage of light, but is quite incapable 

 of forming an inverted image. If any image is formed on the retina it can be 

 little better than a tangle of lines. 



A Shower of Fossils. Lortet. — "Chute de Crustaces ostracodes fossiles 

 observee a Oullins, pres de Lyon, le 24 Septembre 1898 " (Comptes Rendus Ac. 

 Sci. Paris, 1898, cxxvii. pp. 1231, 1232). On a calm evening, about sunset, 

 Lortet observed, near Lyon, a thick and rapid shower of fossil Ostracods 

 (Cypridinia), and heard the minute shells rustle the withered leaves. They 

 had. no doubt been caught in an ascending air-current from some of the regions 

 in North Africa, where they abound. 



