H THE MAIN CURRENTS OF ZOOLOGY 



There now began to rise the suggestion that 

 sarcode and protoplasm were different names for 

 one and the same substance and, in 1850, Ferdinand 

 Cohn definitely maintained that protoplasm and 

 sarcode were identical substances. Later in life Cohn 

 became eminent for investigations in bacteriology 

 but, at this time he was a young man of twenty-two 

 years and his contribution was considered theoretical 

 and insufficiently supported by observation and ex- 

 periment. 



With Max Schultze (1825-1874), came the summa- 

 tion of the accumulated knowledge regarding proto- 

 plasm and the final step in bringing it into full 

 recognition in the scientific world. After a long 

 series of observations and experiments he announced, 

 in 1861, that living substance, be it called sarcode or 

 protoplasm, is essentially alike in animals and plants. 

 He reached this conclusion largely upon physiological 

 resemblances, pointing out, especially, that the con- 

 tractility exhibited by all protoplasm is essentially 

 similar to the contraction of muscles. 



One thing that had stood in the way of an earlier 

 recognition of the true nature of protoplasm was, 

 that for some years, it was supposed to be confined 

 to lower animals and it was necessary that observa- 



