528 



SCIENCE. 



[N. S. Vol. XXIII. No. 5S8. 



that the animals that have lived in media 

 , containing OH ions have a lower resistance 

 to HCl than the animals that have lived in 

 media containing H ions. Colpidia have 

 a higher resistance than Paramcecia, for 

 both H and OH media. The HCl + NaCl 

 solution has a greater effect on both Para- 

 ma'cium and Colpidium than the same con- 

 centration of HCi used alone would have. 

 Experiments here made show that the NaCl 

 used alone is physiologically favorable. 

 The increased effect when both are used is 

 due to greater gram ionic concentration of 

 H which would be expected in the mixed 

 solutions in accordance with conductivity 

 measurements of Lincoln and of Jones and 

 Knight. 



Phagocytosis in a Mammalian Embryo: 



M. M. Metcalf, Oberlin College. 

 On the Bole of the Substantia reticularis 

 in the Evolution of the Vertebrate Brain: 

 J. B. Johnston, University of West 

 Virginia. 



The vertebrate nervous system consists 

 of somatic sensory, visceral sensory, somatic 

 motor and visceral motor divisions. Each 

 of these divisions is represented by central 

 and peripheral structures in each segment 

 of the head and trunk, except where the 

 organs to be innervated are wanting. The 

 central portion of each division constitutes 

 a continuous zone or column in the spinal 

 cord and brain. These longitudinal 

 columns are the fundamental divisions of 

 the central nervous system. In addition 

 to these there are in the central system 

 numerous cells which are left over after 

 the four main columns are differentiated. 

 These cells serve functions of connection 

 and correlation between the four columns 

 and between distant segments of the cen- 

 tral system, and constitute the substantia 

 reticularis grisea. The cells of the sub- 

 stantia reticularis are indifferently scat- 

 tered throughout the four divisions, and 



when one or other division is absent they 

 form the whole gray matter in its place. 



The very important role which this sub- 

 stance plays in the formation of higher 

 brain centers is illustrated by the gustatory 

 and olfactory centers and by the evolution 

 of the cerebral hemispheres. The gusta- 

 tory central apparatus in fishes includes a 

 secondary nucleus in the cerebellar seg- 

 ment and a tertiary nucleus in the inferior 

 lobes of the diencephalon. Both of these 

 are probably differentiated from the sub- 

 stantia reticularis occupying the primitive 

 visceral sensory zone. The relations of 

 these structures in fishes should serve as a 

 guide in discovering the gustatory centers 

 in man. The olfactory apparatus has sec- 

 ondary nuclei in the f orebrain and tertiaiy 

 nuclei in the inferior lobes and in the nuclei 

 habenulffi of the diencephalon. These 

 tertiary centers belong to successive neuro- 

 meres of the primitive brain and to the 

 same chief zone. The cerebral cortex comes 

 from two sources. The one is the visceral 

 substantia reticularis called epistriatum in 

 lower fishes, which forms the hippocampus. 

 The other is an unknown starting point 

 possibly identical with the center of the N. 

 terminalis in fishes, which forms the gen- 

 eral pallium whose functions are primarily 

 the direction of actions with reference to 

 the outside world. 



A New Form of Cutter for Wax Plates: E. 



L. Mark, Harvard University. 

 An Oil-Immersion Paraffine Bath: George 



Lepevre, University of Missouri. 



A paraffine-bath was described which has 

 been designed upon a new principle. Each 

 cup or vessel used for holding paraffine is 

 suspended in a well containing oil, which 

 is, therefore, in contact with the sides and 

 bottom of the vessel. By the application 

 of heat through the mantle of oil, a uni- 

 form temperature throughout the paraffine 

 is obtained, and, owing to the low con- 



