144 CHARLES R. STOCKARD 



The Lot Bs had germ-rings also a little more than half over the yolk, 

 though here again a great many were not developing at all. 



The 6-day-old control presented black and red chromatophores 

 full}^ expanded on the yolk-sac and the embryo. The circulation was 

 completely estabhshed both within the embryonic body and on the 

 yolk-sac. The embryos had begun twitching and moving their bodies. 



Lot Bi had now been at room temperature for 4 days after having 

 been arrested for 45 hours at a temperature of 5°C. The embryos 

 were small with no circulation, almost all seemed abnormal at the 

 head end and many were short; the tail region was not properly formed. 

 They were thus far behind a usual 4-day embryo. 



Lot B2, after now developing at room temperature for 3 days, con- 

 tained many small cyclopean and otherwise defective embryos, but the 

 majority of eggs had stopped and did not develop beyond the condition 

 shown by them after the 70-hour stay at 7°C. 



Lot B3 contained some fairly regular 3-day embryos, but with no 

 circulation, and many of these were deformed. 



Seven days after fertilization the blood-vessels of the control 

 embryos were well mapped out by the alignment of pigment and the 

 embr3^os themselves were vigorously active. 



Lot Bi contained at this time many well-formed embryos with good 

 circulation, pigment migration, etc. Others had a sluggish and poorly 

 established circulation, some showed a heart beat, but no circulation, 

 and many more had stopped in development and the cells had wan- 

 dered apart to lie over the yolk surface. Some eggs presented simply 

 yolk-sacs with blood-spots scattered over them, but without an em- 

 bryo. A few of the apparently well-formed embryos were abnormal 

 in various ways. 



Lot B2 showed no circulation, many eggs did not develop, and almost 

 all were readily seen to be abnormal. The lot B3 also showed no cir- 

 culation, but contained some well-formed embrj^os just about in con- 

 dition for the heart beat to begin. 



When 9 days old, the control contained all fine vigorous embryos. 



Lot Bi still showed those with only blood and pigment on the yolk-sac, 

 with no embryonic body present. Others still had the cell-mass confined 

 to the upper yolk-pole and there were a few abnormal embryos, some 

 with and others without a circulation. The majority of the living 

 specimens were now normal in appearance with a vigorous circulation, 

 as if some degree of regulation and recovery had taken place 



Lot B2 contained many apparently normal embryos with a good 

 circulation, while some were small and some were abnormal without a 

 circulation. Some eggs showed the old mass of early cleavage cells 

 at the upper yolk-pole still alive after 9 days, though not developing; 

 the cell-masses were irregular and the individual cells spherical in form. 

 Several yolk-sacs also contained blood-cells and a few pigment cells, 

 although no embryo was present. 



Lot B3 contained a few eggs with early cell-masses similar to those 

 in lot B2. The large majority of the surviving individuals now seemed 



