iv GENEEAL PHYSIOLOGY OF NEEVOUS SYSTEM 275 



nerve-centres. The chief result of Battelli's experiments is'that 

 calcium salts appear to be essential to the gaseous exchanges 

 between the circulating fluid and the nerve-centres. 



Some recent experiments of Sabbatani also confirm the 

 importance of calcium to the normal functions of the centres of 

 the cerebral cortex. 



Baglioni (1904) further instituted a series of experiments on 

 his preparation of the frog's isolated spinal cord, with the object 

 of determining the conditions under which salt solutions are able 

 to maintain the reflex activity of the nerve-centres. In particular 

 he investigated the importance of sodium chloride, and found that 

 it cannot be replaced by any other substance, e.g. glucose, glycerol, 

 asparagine, etc., or by potassium or lithium chloride at equal 

 concentration. Sodium chloride can only be replaced to a certain 

 extent by other salts of sodium (bicarbonate, nitrate). 



If the isolated spinal cord is placed in an isotonic solution 

 which contains, e.g., glucose instead of sodium chloride, its reflex 

 excitability disappears after a certain time (two to five hours 

 according to the surrounding temperature), and returns again if 

 the preparation be immediately plunged into a solution containing 

 Q'6-0'9 per cent sodium chloride. Peripheral nerves react in the 

 same way. 



Lastly, it must be noted that Herlitzka (1909) instituted a 

 series of researches with artificial circulation through the bulbar 

 centres of the frog, in order to determine the chemical conditions 

 of the artificial solutions which are able to maintain their 

 activity. Among other points, he finds that a series of organic 

 substances, such as glucose, glycerol, and urea, added to normal 

 saline enable the centres to survive for a comparatively long time. 

 He attributes the action of these substances to their solubility in 

 lipoids. 



BIBLIOGRAPHY 



The student will find copious references to the early literature of this subject in 

 HERMANN'S Text-book of Physiology, and to the later in those of SCHAFER and 

 NAGEL. 



Morphology of Nervous System : 



WALDEYER. Deutsche med. Wochenschr., 1891. 



RAMON Y CAJAL. Revista de cientias medicas de Barcelona, nums. 16, 20, 22, 23, 



1892. Arch, di fisiol. vol. v., 1908. 



NISSL. Allgem. Zeitschr. f. Psychiatric, vol. xlviii., 1892. 

 APATHY. Mitteil. a. d. zool. Station zu Neapel, 1897. 

 BETHE. Arch. f. raikrosk. Anat., 1897. Morphol. Arbeiten von Schwalbe, 



vol. viii., 1898. Biol. Centralblatt, xviii., 1898. Arch. f. mikrosk. Anat. 



vol. Iv., 1900. Allg. Anat. u. Physiol. d. Nervensystems. Leipzig, 1903. 

 ROBERTSON. Brain, Part Ixxxvi., 1899. 

 GOLGI. Boll, della Societa Med. Chir. di Pavia, 1898-99. Verhandl. d. anat. Ges. 



XIV. zu Pavia, 1900. Arch, di fisiol. vol. iv., 1907. Atti della Soc. ital. p. il 



progresso d. scienze, III. Riunione, 1910. 

 DONAGGIO. Riv. sper. di freniatria, 1896, 1900, 1904, 1905, 1908. Int. Congress 



of Physiology. Turin, 1901 ; Brussels, 1904. 



