In many respects, the steroids also seem to fall within this class. This enormous generalization induced from structure determination studies led to the hypothesis that all of these molecules are made in the cell by a single route â that they are products of a common biogenetic pathway. In recent years, great progress has been made in mapping this pathway.
Captain definition, a person who is at the head of or in authority over others; chief; leader. See more.
1 O Captain! My Captain! at the start of the first two stanzas are examples of apostrophe, as is Exult O shores, and ring O bells! in the third stanza.  The poet refers to the fallen captain as father, representing his deep respect for president Lincoln and Lincoln's role as father of the Union.