DEVELOPMENT WITHOUT MEMBRANE FORMATION 221 



also with a mixture of sea-water and pig's serum without 

 the addition of SrC^. 1 But at this time the writer was not 

 yet familiar with the gelatinous form of membranes in the 

 eggs of this species, and so he must leave it in doubt whether 

 or not gelatinous membranes were formed in the eggs which 

 developed. 



The following hitherto unpublished experiments are rather 

 curious. Unfertilized eggs (without membranes) were placed 

 in m/2 sodium butyrate solution and taken out from it at differ- 

 ent intervals. The solution was strongly alkaline (requiring 

 4.2 c.c. N/10 HC1 [per 50 c.c. of solution] to turn neutral red 

 from yellow to red). 



A large number of the eggs formed membranes, but most of 

 these (if not all) succumbed to cytolysis. However, a small 

 number (about 1 per cent) of the eggs removed after between 

 three and four hours developed into swimming larvae. These 

 eggs possessed either no membrane or only one that adhered 

 very closely to the egg, probably a gelatinous membrane. The 

 experiment was repeated with a sodium butyrate solution of 

 much diminished alkalinity. The amount of cytolysis (and 

 membrane formation) was reduced by this, but the activation 

 of a few eggs took place in this case also (but not, of course, 

 before the eggs had been transferred to normal sea-water). 

 About 2 per cent of the eggs that had been about six or seven 

 hours in the sodium butyrate solution developed into swimming 

 larvae. I believe that in both these cases a gelatinous mem- 

 brane was formed, but the remarkable fact is that the eggs 

 developed to the blastula stage at room temperature without 

 subsequent treatment with a hypertonic solution. Could it be 

 possible that the butyrate solution acted like a solution in 

 which oxidations were prevented ? 



3. E. P. Lyon succeeded in causing artificial partheno- 

 genesis in Arbacia pustulata and Strongylocentrotus lividus at 



iLoeb, Pfluger's Archiv, CXXIV, 50, 1908. 



