A Physiological Study of the Changes in Mustelus Canis Produced by Modifications in the Molecular Concentration of the External Medium

CONTENTS Paw Introduction ......................................................... 2 Historical sketch ...................................................... 5 Normal osmotic pressure of the bloocl of Muslclu8 ....................... 6 Chnnges in the osmotic pressure of the bioozl due to alterafions In t h e concentration of the external mediom ................................ 8 Preliminary study ................................................. 8 Changes from the normnl condition until death in fresh water and concentrated Ben.water ........................................... 11 Reverse canges brought nbout by. a return to sea-water after irumei. sion of the orgnnirsm In fresh water and concentrated sea-water .... 22 Role of the gills I n the osmotic, changes of the blood ..................... 25 Osmotic pressure of the bloocl of an elnsmobraiicb taken from brackish water .............................................................. 30 Effect of loss of blood on the osmotic pressure of the blood ............. 34 Additional changes In . the blood due to nlteratioos in the concentration of the external medium ................................................ 36 Changes In the erythrocytes ......................................... 36 Changes in the specific gravity of the blood ......................... 44 Cbnngea Iu the percentage composition of the water and tbe solids of the blood ........................................................ 44 Changes In the nitrogen conteut of tbe blood ...................... : .. 46 Changes in the urea o f the blood .................................... 47 Changes In the sal t of the blood ..................................... 48 Regulatlon of the osmotic pressure of tbe blood ......................... 51 Presence of salts in the erternal medium after immersion of dfustcirs in fresh mater ......................................................... 51 Effects of changes in the osmotic pressure of the blood on blood pressure. respirntlon and cardiac activity ...................................... 55 Dlscuselon ........................................................... 63 Coneludons .......................................................... 71 Bibliography ......................................................... 73