EXTRACT XII. A. 



ON THE GENERAL BEARINGS, AND ROLE, OF THE 

 HAEMAL LYMPH AND THE CEREBRO-SPINAL FLUID. 



THAT the haemal lymph, or fluid, is the earliest differen- 

 tiated fluid in the economy of the fecundated ovum, or in 

 the pre-existent germ and sperm cell elements, as well as 

 in the resultant, or sequential, embryo, is abundantly 

 obvious as a fundamental embryonic truth, and that it 

 continues, in conjunction with the more lately elaborated 

 cerebro-spinal lymph, to play a most important part in the 

 economy of the growing organism, is equally obvious to the 

 anatomist and physiologist, while, as the life of that organ- 

 ism lengthens out into even the senile stage, it continues 

 to be observed by the clinician to exercise a profound 

 influence on its progress in relation to its functional work, 

 its freedom from the attacks, and its power of resistance, of 

 pathogenic influences and agencies. 



Thus, in the embryo, we see the early, or nascent, struc- 

 tures and organs evolve themselves within and inter-pene- 

 trated by this haemal lymph fluid, and that it is gradually 

 displaced by the accumulating neural lymph, as the various 

 structures increase in consistence and volume, and become 

 differentiated into anatomical and physiological systems and 

 entities, until the arrival of the period of post-natal, or 

 independent, existence finds the neural lymph, in turn, rele- 

 gated to the central spaces of the brain and cord and to the 

 peripheral, or inter-meningeal, and the inter-neurilemmar 

 spaces of brain, cord, and nerves respectively, and to the 

 dually innervated structures generally, where it, the neural 

 lymph, continues its gradually restricted role of mechanical 



