286 RALPH S. LILLIE. 



Control lots of eggs were exposed (for purposes of comparison) to 32° for single 

 continuous periods ranging from 2 minutes to 10 minutes. 



After-exposures to 32° at Follow- Results (Condition of Eggs ca. 4 Hours Later, and 



ing Times after First Exposure. Proportion Forming Larvae. 



1. Control: no second ex- 



posure All mature eggs have membranes but are uncleaved 



and largely irregular in form. None form larvae. 



2. 9 m. (11. 24-11. 28) (no 



polar bodies at 11.28). . .Marked contrast to control; almost all eggs are 

 cleaved, largely to 32- or 64-cell stages. Ca. 70-80 

 per cent, form larvae many of which swim at the 

 surface of the water. 



3. 19 m. (11.34-11.38) 



(first polar bodies be- 

 ginning to separate at 

 11.38) Cleavage is less advanced than in Experiment 2, and a 



minority are uncleaved. Somewhat fewer larvae 



{ca. 65-75 per cent.). 



4. 29 m. (11. 44-11. 48) 



(first polar bodies in all 



eggs at 11.48) Cleavages are fewer and less advanced than in Ex- 

 periment 3. Most eggs are uncleaved. Larvae 

 fewer {ca. 30-40 per cent.). 



5. 39 m. (11.54-11.58) 



(all with first polar 



bodies, none with 



second at 11.58) Contrast to Exp. 4; great majority are uncleaved and 



largely irregular; a few 2- and 4-cell stages present; 



few form larvae {ca. 5 per cent.). 



6. 49 m. (12.04-12.08) {ca. 



50 per cent, have 

 second polar body at 



12.08) Similar to Exp. 5 but with fewer cleavages. Larvae 



also are fewer {ca. 2-3 per cent.). 



7. 59 m. (12. 14-12. 18) 



(all eggs have second 



polar bodies) Nearly all are uncleaved; largely irregular or frag- 

 mented. Almost no larvae (only one feeble blas- 

 tula seen). 



8. I h. 9 m. (12.24-12.28).. .All are uncleaved but irregular forms are fewer. No 



larvae. 



9. ca. 3 h. (2.59-3.03) Similar to Exp. 8. 



Controls with one exposure to 32°: eggs exposed 7 minutes continuously (11. 12- 

 II. 19) gave ca. 90 per cent, larvae. With 4 minutes' exposure few eggs {ca. 2-3 per 

 cent.) formed larvae. Controls of unfertilized and sperm-fertilized eggs were normal. 



