218 



PROTOPLASM 



diiim may be of fairly high consistency. This is particularly 

 noticeable when large masses of it hang freely suspended from the 

 sides of a culture dish {A, Fig. 109) or form substantial columns 

 between roof and floor of the culture dish {B, Fig. 109). Within 

 such a rope of protoplasm, the inner mass is actively streaming. 

 There has been some unnecessary confusion in regard to 

 viscosity values of protoplasm. One group of workers insists 

 on low values, while the other lays emphasis on high. Both 

 are right in part, as protoplasm runs the entire range in viscosity 





A B 



Fig. 109. — Ropes of protoplasm; A, hanging freely; B, forming a column. 



(with the exception of the very lowest values), but there is a 

 preponderance of higher values. Scarth compares the matrix 

 of plant cytoplasm to a soft gelatin jelly and adds that even in 

 its streaming condition protoplasm is viscid and highly extensile. 

 This it would have to be in order to maintain strands freely 

 suspended which yet show streaming within. Mudd uses the 

 irregular form which white blood cells (leucocytes) maintain, 

 even when subjected to tension, as an indication of the very high 

 viscosity of the protoplasm. Runnstrom finds one (unfertilized) 

 echinoderm egg (Echinocardium) to have a high viscosity value, 

 while another (Arbacia) has a much lower value. 



It is impossible to draw general conclusions as to the viscosity 

 of protoplasm from one kind of material. The fact that proto- 

 plasm flows suggests low consistency; but strand formation, 

 tensile strength, irregular form, imbibition, elasticity, and adsorp- 



