1064 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [84] 



of silver aud then washed it with salt solution. Branched connective 

 tissue cells collect around the inflamed spot and eat up blood corpus- 

 cles, carmine granules, and particles of pigment. * * * When a 

 fully-gorged phagocyte dies it is immediately devoured by another. 

 Inflammation then is not, as is ordinarily supposed, due primarily to a 

 morbid condition of the walls of the blood vessels; it is a struggle be- 

 tween phagocyte and septic material, and it is in Vertebrates alone that 

 the vascular system, owing to the insufiicieut number of extra- vascular 

 phagocytes, takes part in the struggle."* 



The exaltation of metabolism shown in phagocytic phenomena ac- 

 counts for the rise in temperature when they are manifested in the 

 higher forms. It is not singular that the storage of proteids in cells 

 should occur in certain cases, especially where these are destined to be- 

 come greatly exaggerated in amount in order to aflbrd the pabulum from 

 below to the gi'owing blastoderm and embryo, which is superimjiosed 

 upon a supply of proteinaceous matter known as the yelJc, which in turn 

 is literally consumed by cells of hypoblastic origin (megasphfera) or by 

 a plasmic layer standing in a similar relation to the embryo, as fast as 

 the yelk material is needed for the growth of the latter.t The primi- 

 tive egg-cell of the ovary may, therefore, in one sense, be looked upon 

 as a phagocyte of a special kind iu such forms as develop a yelk. 



Just beneath the hypoblast of the yelk of the Kays there exists a 

 stratum of singular amcebiform cells, which are uuich branched and 

 irregular in form. They are not in contact with each other except by 

 their pseudopodal prolongations. They contain coarse granules in the 

 central parts, which are doubtless disintegrated vitelline tablets which 

 have been taken in from the true yelk below and converted into their 

 own more mobile protoplasmic substance. These bodies are quite outside 

 of and below the hypoblast and vascular mesoblast. The apparatus for 

 the absorption of the yelk of the Elasmobrauch vitellus is therefore 

 quite different from that which is found in the Teleosts, as may be 

 learned upon consulting the papers by the writer last cited, where he 

 has described the homogeneous converting layer in the eggs of the 

 latter group, calling it the yelk hypoblast for reasons which appear valid,, 

 because its function is a temi)orary one, the structure disappearing with 

 the necessity for its existence. 



The quasi-phagocytic action of primitive ovicells,! in consequence 

 of which the germinative vesicle or nucleus suffers displacement, just as 

 the cells of the notochord and adipose tissues have their nuclei displaced 



*E. Metschnikoflf. Qnar. Jonrn. Mic. Sci., XXIV, p. 112-117. 



t Development of the Silver Gar {Belone longirostria), with observations on the gen- 

 esis of the blood in embryo fishes, and a comparison of fish ova with those of other 

 vertebrates. Bull. U. S. Fish Comm., I, pp. 283-301, 1831. 



Observations on the mode of absorption of the yelk of the Embryo Shad. Bull. U. S. 

 Fish Comm., II, pp. 179-187, 1882. 



t The law of nuclear displacement, and its significance in embryology. Science, I, 

 1883, pp. 273-277, 



