68 CHARLES PACKARD. 



EXPLANATION OF PLATES. 



The drawings were made with the aid of a camera lucida. The lenses employed 

 were a 1.5 mm. Zeiss Apochromatic and a No. 6 Compensating ocular. 



EXPLANATION OF PLATE I. 



FIG. i. Normal fertilization. 25 min. after insemination. 



FIG. 2. Egg radiated for 80 min. The development of the sperm is abnormal. 



FIG. 3. Egg radiated 35 min. Killed 34 min. after insemination. 



FIG. 4. " 30 min. " 



FIG. 5. " " 39 min. " 



FIG. 6. " 39 min. " 



