IN ONTOGENESIS 



803 



further his view that the properties of the membrane were the con- 

 trolHng factors in egg permeabiHty, Gray put a list of haemolytic 

 agents next to a Hst of parthenogenetic agents, and emphasised their 

 general resemblance ; Dalcq has followed this relation further in his 

 book on fertilisation, which should be consulted for further details. 



The work of Gray and McClendon on the conductivity of echino- 

 derm eggs was extended by Bataillon to the eggs of amphibia. 

 Bataillon found in their case also a regular decline in electrical re- 

 sistance after fertiUsation, but his results differed from the final ones 

 of Gray, in that with the frogs there was always a gradual return to 

 a level slightly less than that of the unfertilised eggs. The percentage 

 decreases were as follows : 



Percentage decrease of 



electrical resistance 



on fertilisation 



Ranafusca (parthenogenesis) 

 Rana esculenta (fertilisation) 

 Bufo calamita (fertilisation) 



12-35 

 19-65 



which agree well with those found by Gray, Bataillon's data are 

 plotted in Fig. 189. He reported that the hepatopancreatic juice 

 of the crab would destroy unfertilised amphibian eggs, but not fer- 

 tilised developing ones (jelly ^ o ® 

 having been removed in both 

 cases), yet this immunity did 

 not appearuntil after 30 minutes 

 from fertilisation. He thought 

 that the decreasing membrane 

 permeability as measured in 

 terms of electrical resistance 

 might be connected with this 

 fact. 



Other investigations of per- 

 meability of marine egg-mem- 

 branes were those of McCut- 



1-200'- 

 ohms 



Fei-t. 



20 30 40 50 60 

 Minubes after fertilisation 



Fig. 



cheon & Lucke, who found that in solutions of hydrochloric acid, 

 sodium hydroxide, carbon dioxide and ammonia no swelling of 

 Arbacia eggs occurred, and they decided that the membrane was 

 normally almost impermeable to these substances. Lillie made 

 similar experiments. Driesch and Konopacki studied the cytological 

 effects of raising echinoderm eggs in hypotonic sea-water. Faure- 



