Physical Properties of Protoplasm 155 



exhibited by the living cytoplasm. Small fragments of the dead 

 nuclear gel do not go into solution when dissected out in sea water. 



AMEBA PROTEUS 



Small pieces of ectoplasm of proteus can be cut off in distilled water 

 and show no change. This living substance has a moderately high 

 viscosity and cohesiveness ; it does not stick to glass needles very 

 readily and little difficulty is experienced in cutting it into pieces as 

 small as the limit of microscopical visibility. Pieces of all sizes 

 appear perfectly homogeneous. The cloudiness of the ectoplasmic gel 

 is a well-known property. The inner three or four microns of the hya- 

 line ectoplasm and particularly the interior of the outer end of small 

 pseudopods, contain varying numbers of minute granules and glob- 

 ules that may measure as much as four or five microns. If these gran- 

 ules and globules are dissected out they do not go into solution. 

 The globules show confusing diffraction rings ; but, both globules and 

 granules can be brought out by light staining with diethyl-safranin- 

 azo-dirnethyl-anilin. The endoplasm contains a large contractile 

 vacuole in which the presence of protein has not been demonstrated, 

 as yet, and numerous food vacuoles which contain either liquid or 

 liquid and food masses. The same kind of granules and globules 

 are found in the endoplasm as are found in the ectoplasm and the 

 number of these structures varies in different animals. The sub- 

 stance forming the walls of the vacuoles is of much higher viscosity 

 and cohesiveness. The living endoplasmic substance is a very dilute 

 and apparently homogeneous gel that possesses a remarkable affinity 

 for water. The ectoplasm of ameba then is a quite concentrated gel 

 while the interior is quite dilute and is continously changing its water- 

 holding power in different regions. New methylene blue R and 

 trypan blue are of great value in bringing out the globules, granules 

 and vacuoles. 



The nuclear membrane is an extremely thin and moderately tough 

 solid substance. It shows some elasticity and is quite viscous. 



The whole of the nuclear substance is a highly rigid and granular 

 gel, the minutest pieces of which show no appreciable change when 

 dissected out in distilled water. A slight elasticity and a definite 



