Mantle-folds, the.
Marsupials, the. ova of the.
Materialism.
Mathematical method, the.
Mechanical causes. embryology.
Meckel's cartilage.
Medulla capitis, the. oblongata, the. spinalis, the.
Medullary groove, the. tube, the. formation of the.
Mehnert, E., on the biogenetic law.
Meroblastic ova.