418 THE BLOOD, BY ALEXANDER ROLLETT. 



After the continuous application of strong shocks the white 

 corpuscles become destroyed, molecular movements occur in 

 the swollen cells, or they are ultimately reduced to disks, and 

 discharge their granules. A great number of these cells can 

 be observed in an isolated condition if a drop of blood, recently 

 obtained from a Newt or Frog, be brought upon a glass cover 

 placed over a moist cell, and the drop, whilst freely dependent, 

 allowed to coagulate. It is soon observable, when the zone of 

 serum extends beyond the limits of the clot, that in this zone, 

 in .consequence of an active migration from the coagulum, 

 numerous amoeboid cells are present, and that they have 

 accumulated on the surface of the coagulum. 



Sclarewsky* has discussed this phenomenon of the migration 

 of the white blood corpuscles from the coagulum at consider- 

 able length, as it may be observed in blood coagulated in 

 capillary tubes. The above-mentioned simple experiment is far 

 better adapted for the isolation of the cells for microscopical 

 observation, and the investigations which can thus be made 

 into the details of the migration of the individual cells renders 

 it clear that the individual movement of the cells is the chief, 

 if not the exclusive, cause of their emigration. The causes 

 which must be admitted for the movements leading to this 

 migration are still to be ascertained. 



Besides these migrating cells a few small colourless structures, 

 presenting the appearance of free nuclei, occur in the blood of 

 the Frog at all periods of the year ; lastly, we meet, in the blood 

 of the frog, with the fusiform cells, first exactly described by 

 Ton Recklinghausen,-f- which, however, vary in number with 

 the period of the year, being especially abundant in spring. 

 They possess a bright homogeneous cell substance, and a granular 

 oval nucleus. 



Yon Recklinghausen, who has acquainted us with the remark- 

 able fact that if the freshly drawn blood of the Frog be pre- 

 served in moist air, after a short time an active process of cell 

 formation takes place in it, which ultimately leads to the 

 formation of red blood corpuscles, has also furnished some 



* Pfluger's Archiv, 1868, p. 660. 



t Max Schultze's Archiv, Band ii., p. 137. 



