70 PROGRESS OF MICROSCOPICAL SCIENCE. 



surfaces or particles coming in contact are liable to become attached 

 thereto. Some phenomena observed lend countenance to a theory 

 that this membrane is dotted with minute pores which permit delicate 

 threads of the soft protoplasm it encloses to be extruded, and that the 

 edges of these foramina, if the projection still continues, are carried 

 outwards during the amoeboid movement, forming a sheath to all except 

 the extreme point of the tongue-like process. The material occupying 

 the space between the capsule and the nucleus, denominated the pro- 

 toplasm of the cell (the fibrino-plastin of Prof. Heynsius), is a soft 

 jelly-like matter in which chiefly resides the capacity of amoeboid 

 motion. This protoplasm appears to be soluble in water and saline 

 solutions in all proportions, and when freely diluted loses its amoeboid 

 power, which, however, is regained in a majority of cases, when the 

 excess of fluid is removed. The laws by which leucocytes take up 

 and part with fluid seem to be simply those of the dialysis of liquids 

 through animal membranes by endosmosis and exosmosis, as investi- 

 gated on a larger scale by Graham in 1855 ; the rapid inward current 

 from the rare solution of high diffusive power, through the cell wall, 

 distending that membrane and diluting the contained fluid, until an 

 equilibrium of the endosmotic and exosmotic flow is attained, or the 

 capsule is burst by the centrifugal pressure of accumulated liquid. 

 " The structure of the particles which exist in the protoplasm and 

 exhibit dancing motions when the latter undergoes dilution is yet 

 undetermined, although sundry facts indicate that their movement is 

 not dependent on 'vital' causes, but is merely a molecular one; also 

 that some of them, at least, are minute granules of fatty matter which 

 after a time may coalesce into visible oil globules, as in the older pus 

 corpuscles. In regard to any difference of their motion in the sali- 

 vary bodies, my experiments as above detailed so fully and uniformly 

 corroborate each other, that, reluctant as I feel to dispute the as- 

 sertions of such celebrated histologists as Strieker and Pfluger, I 

 cannot but call in question the general correctness of their statement 

 upon this point ; for it is manifestly inaccurate to affirm that a half 

 to one per cent, salt solution still permits the ' dancing' movements 

 of fresh pus or lymph corpuscles to continue, when the fact is that 

 the motion ceases in nineteen out of every twenty globules under its 

 action, just as it would be erroneous to maintain that quinine does not 

 stop the course of ague, because in one case out of twenty it fails to 

 prevent a recurrence of the chill. I therefore am induced to think, 

 from the above investigations, which I trust any critic will do me the 

 justice to repeat before disputing, that, contrary to the views of these 

 histologists, no essential difference exists in the effects of salt solu- 

 tions of various strengths upon the salivary, pus, and white blood 

 corpuscles ; and from this circumstance, in conjunction with the in- 

 teresting fact discovered during one of my experiments, that the sali- 

 vary globules, when acted upon by the denser saline liquid, contract 

 to the size of the blood leucocytes, and manifest amoeboid movements, I 

 conclude my theory, that the corpuscles of the saliva are 'migrating' 

 white blood globules, which, ' wandering out' into the oral cavity, 

 have become distended by the endosmosis of the rarer fluid in which 



