PROTOPLASM. 



continuous throughout the tube. We do not see the prominent 

 radiations of strands around a large nucleus, but still the proto- 



Fig. 6. 

 Colonies of mucor. 



plasm does not fill the interior of the threads. Here and there 

 are rounded clear spaces termed vacuoles, which are filled with 

 the watery fluid, cell-sap. The nuclei in mucor are very mi- 

 nute, and cannot be seen except after careful treatment with 

 special reagents. 



15 Movement of the protoplasm in mucor. While exam- 

 ining the protoplasm in mucor we are likely to note streaming 

 movements. Often a current is seen flowing slowly down one 

 side of the thread, and another flowing back on the other side, 

 or it may all. stream along in the same direction. 



16. Test for protoplasm. Now let us treat the threads with 

 a solution of iodine. The yellowish-brown color appears which 

 is characteristic of protoplasm when subject to this reagent. 



