The last course that I heard from Agassiz in Cambridge began on
October 23, 1867, and closed on January 11, 1868. It was memorable for
him and for me. At the outset he announced that some progress had been
made in the University toward the adoption of an elective system for
the students, and that he proposed to apply the principle to his own
instruction, and should devote the entire course of twenty-one lectures
to the Selachians (sharks and rays), a group in which he had been
deeply interested for many years, and upon which he was then preparing
a volume. This limitation to a favorite topic inspired him to unusual
energy and eloquence. My notes are quite full, but I now wish the
lectures had been reported verbatim. This course was signalized also by
two special innovations, viz.: the exhibition of living fish, and the
free use of museum specimens. That, so far as possible, all biologic
instruction should be objective was with Agassiz an educational dogma,
and upon several notable occasions its validity had been demonstrated
under very unfavorable conditions. Yet, during the five years of my
attendance upon his lectures, they were seldom illustrated otherwise
than by his ready and graphic blackboard drawings. The simple fact was
that the intervals between his lectures were so crowded with
multifarious, pressing, and never-ending demands upon his time and
strength that he could seldom determine upon the precise subject long
enough in advance for him, or any one else, to bring together the
desirable specimens or even charts. The second lecture of the course
already mentioned is characterized in my diary as 'splendid,' and as
'for the first time illustrated with many specimens.' At one of the
later lectures, after speaking about fifteen minutes, he invited his
hearers to examine living salmon embryos under his direction at one
table, and living shark embryos under mine at another.

Like those of Wyman, the courses given by Agassiz were Senior