THE ARTIFICIAL PRODUCTION OF SPORES. 171 



Experiment III. On May 14 a culture of Monas was placed 

 on ice at a temperature of I C. On May 22 a large number 

 of the resting cells and spores were removed to the room tem- 

 perature and isolated under the microscope in closed cells that 

 contained fresh-water algae. Development of the spores com- 

 menced at once, and on May 25 they had reached the motile 



Monad form. 



SUMMARY. 



1. In Fionas a reduction of the temperature brings about cer- 

 tain structural changes within the cell, that result in the formation 

 of many small spores, each of which has the power of reproduc- 

 ing the organism. 



2. It is thus possible by means of variations in the temperature 

 to control the methods of reproduction in Monas. At a tem- 

 perature of 20 C. Monas multiplies sexually and by simple fis- 

 sion. At a temperature of i to 4 C. reproduction by asexual 

 spores takes place. 



