Summary

Thanks CD for Origin, 6th ed.

Has declined chair at Strasbourg.

Describes research on calcareous sponges.

Criticises Pangenesis.

Summary

Much experiment and observation needed before spontaneous generation will be empirically advanced, but philosophically the matter is clear.

Thinks Ludwig Rütimeyer has attacked EH to satisfy pious opinion in Basel.

Will soon be finished with his monograph Die Kalkschwämme [1872].

Summary

Thanks CD for Expression.

Describes work on Die Kalkschwämme and its principal conclusions.

The application of biogenetic law.

Notes variability among calcareous sponges.

Gastrula-like "Gastraea" as ancestor of multicellular animals.

Posits homology between Hydra, Olynthus of calcareous sponges, and initial germ layers of higher animals.

Comments on Lubbock’s Prehistoric times [1865]

and on David Strauss’s Der alte und der neue Glaube [1872].