46 MANUAL OF HISTOLOGY. 



forty-eight hours the animals entirely recover, but if a stronger solution is 

 used, he finds the results are frequently fatal, though the animals may survive 

 long enough to 'permit a ready demonstration of the circulation, emigration of 

 leucocytes, etc. 



Now envelop his body in a damp cloth and extend him upon 

 a cork plate about a quarter inch thick and large enough to 

 support the entire body. Make a small opening in the cork, 

 and over it place the web oi the frog's foot, fastening the latter 

 by ordinary pins. 



The circulation may in this way be studied at one's leisure. 

 The red and white blood-corpuscles are seen in the arteries, 

 veins, and capillaries. While the red bodies pass rapidly 

 through the central portions of the vessels, the white creep 

 slowly along the walls, altering their shape as they meet with 

 any obstruction. Where, however, a small artery divides, it 

 will sometimes be seen that the corpuscles, especially the red, 

 are caught at the bifurcation ; parb bending to go down one 

 branch, and part down the other ; taking, in fact, the shape of 

 a saddle-bag. Such a phenomenon exhibits the elastic and 

 distensile properties of the corpuscle. Apply an irritant, such 

 as a weak solution of nitrate of silver, and after prolonged and 

 careful watching, the gradual exit of both white and red cor- 

 puscles may be seen. This procedure requires extreme pa- 

 tience and a co-operation of peculiarly fortunate conditions, 

 which are not likely to favor the beginner in microscopy. 



Internal structure of the red corpuscles. As yet the inti- 

 mate structure .of blood-corpuscles is a matter little understood, 

 though an abundance of theories are rife about it. Klein main- 

 tains that these corpuscles, in common with others in the body, 

 are traversed by an intracellular network. In the red cor- 

 puscles of the newt, especially, he says there is a network of 

 fibrils, with an interfibrillar hyaline ground substance, both 

 together forming the so-called stroma. The nucleus contains a 

 network of fibrils in connection with the network of the cor- 

 puscle proper ; the haemoglobin, a colored fluid, is contained in 

 the substance of the meshes of the network of the corpuscle 

 proper. Drs. Cutter, of Boston, and Heitzmann, of this city, 

 also state that there is an intracellular network. The former 

 regards it as due to the mycelium of a parasitic growth. 



Dr. Elsberg, of this city, also states that he finds a reticu- 

 lar appearance after using a solution of the bichromate of 



