ARTIFICIAL PRODUCTION OF NORMAL LARVAE FROM THE UNFERTILIZED EGGS OF THE SEA URCHIN.

Modern investigations into the mechanism of life phenomena have yielded results of great value. One of the most prominent and original of the investigators in this field is Jacques Loeb, in the Hull Physiological Laboratory of the University of Chicago. Loeb's recent studies into the conditions which influence embryonal development and growth, and into the nature and process of fertilization, are undoubtedly of fundamental importance. He shows¹ that alkalies and acids exercise a pronounced influence on the development of certain salt water larvæ (Arbacia), alkalies hastening their growth. The quantity of alkali necessary is remarkably minute. The addition of 1.5 to 2 c.c. of a decinormal NaOH solution to 100 c.c. of sea water suffices. Acids, on the other hand, retard development and growth. Loeb regards the cause of this action of dilute alkalies and acids on development and growth as due to the fact that weak alkalies favor the