APPENDIX. 53 



Laws i to 4 may be expressed as one the law of 

 combination: Similar parts that are wholly or partly 

 separated have the tendency to unite more and more 

 completely and intimately into one continuous tissue. 



The laws of ampliation (5), differentiation (6), 

 and reduction (7), may be summarized in one as 

 follows : While increasing in size the similar parts 

 of an ontogeny become internally dissimilar and the 

 dissimilarity increases as the transition forms of the 

 dissimilar parts vanish. Hence only the extreme 

 forms remain. 



It may also interest the reader to know that 

 Nageli was the first to propose the general theory 

 of cell formation as accepted at the present day. 



