1905.] Effects of Alkalies, etc., on Eggs of Echinus. Ill 



Caustic Alkalies. 



Sodium Hydrate. 

 Brood* of Eggs No. 1. 



of embryos, at interval after start of experiment given at head of each column. 



24 h. 50 m. 29 h. 15 m. 41 h. 45 m. 70 h. 30 m. 91 h. 50 m. 114 h 



Blastulse. A 

 few moving 



Blastulse. A 

 few moving 



Blastulse. A 

 few moving 



Blastulse. A 

 few moving 



Blastulse. 

 Motionless 



Blastulse. 

 Motionless 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse. All 

 in active 

 motion 



Blastulse and 

 some gastru- 

 lse. All in 

 active motion 



Commencing gas- 

 trulse. Nearly 

 all dead 



Commencing gas- 

 trulse. Nearly 

 all dead 



Commencing gas- 

 trulse. All dead 



Well - developed 

 gastrulse. All 

 active 



Well - developed 

 gastrulse. All 

 active 



Well - developed 

 gastrulse. All 

 active 



All dead, and 

 degenerating 



All dead, and 

 degenerating 



Late gastrulffl. 

 Very active 

 (glass broken 

 by accident) 



Late gastrulse. 

 Not so far de- 

 veloped as No. 4 



Late gastrulse. 

 (Formalin 

 added by mis- 

 take) 



Forming 

 plutei 



eggs is numbered as belonging to the same brood. 



alkali in the earlier stages, especially observable in No. 4 ; the alkali is in excess in the earlier 

 becomes diminished by the C0 2 given off in growth, No. 6 increases and passes the control. 



of which the first (5a) was left unaltered, while the second had - 5 c.c. of N/10 NaOH added to 

 that of 5a, and the embryos remained alive much longer. 



