88 THE STORY OF THE LIVING MACHINE. 



twenty years, far more marvelous have been the 

 discoveries made in connection with that body 

 which has been called the nucleus. Even by the 

 early microscopists the nucleus was recognized, 

 and during the first few years of the cell doctrine 

 it was frequently looked upon as the most active 

 part of the cell and as especially connected with 

 its reproduction. The doctrine of protoplasm, 

 however, so captivated the minds of biologists that 

 for quite a number of years the nucleus was ig- 

 nored, at least in all discussions connected with 

 the nature of life. It was a body in the cell whose 

 presence was unexplained and which did not fall 

 into accord with the general view of protoplasm 

 as the physical basis of life. For a while, there- 

 fore, biologists gave little attention to it, and were 

 accustomed to speak of it simply as a bit of 

 protoplasm a little more dense than the rest. The 

 cell was a bit of protoplasm with a small piece 

 of more dense protoplasm in its centre appearing 

 a little different from the rest and perhaps the 

 most active part of the cell. 



As a result of this excessive belief in the effi- 

 ciency of protoplasm the question of the presence 

 of a nucleus in the cell was for a while looked 

 upon as one of comparatively little importance. 

 Many cells were found to have nucleii while others 

 did not show their presence, and microscopists 

 therefore believed that the presence of a nucleus 

 was not necessary to constitute a cell. A German 

 naturalist recognized among lower animals one 

 group whose distinctive characteristic was that 

 they were made of cells without nucleii, giving 

 the name Monera to the group. As the method 

 of studying cells improved microscopists learned 

 better methods of discerning the presence of the 



