FOUNDATIONS 3 



In 1839 Schwann's view was stated thus : " The Cytoblas- 

 tema, or amorphous substance in which new cells are to be 

 formed, is found either contained within cells already existing, 

 or else between them in the form of intercellular substance. 

 ... In cartilage it is very consistent and ranks among the 

 most solid parts of the body ; in areolar tissue it is gelati- 

 nous ; in blood quite fluid. ... In plants, according to 

 Schleiden, the nucleolus is first formed, and the nucleus 

 around it : The same appears to be the case in animals." 



In 1841 Kemak described direct division of nuclei, and 

 in 1873 Anton Schneider described indirect division (karyo- 

 kinesis or mitosis). Coming to a more recent date I will 

 refer, and I do so with affection and gratitude, to Edmund 

 B. Wilson's " The Cell in Development and Inheritance," 

 2nd edit., 1904. It is to be remembered that when Wilson 

 wrote generative chromidia had not been discovered. 



This premised, one passage may be quoted, p. 294 : 

 " It may now be taken as a well-established fact that the 

 nucleus is never formed de novo, but always arises by the 

 division of a pre-existing nucleus." 



Now, many chromidia, such, for instance, as some of those 

 of the protozoon Mastigella vitrea, arise for the very purpose 

 of making nuclei de novo, which is the same thing as free 

 nucleus -formation. 



Disagreement between facts such as this and the generali- 

 sation just quoted are considered in Part III, 1912. Some 

 points call for restatement. Let us glance again at pictured 



