GENERAL PROPERTIES OF THE ECTOPLASM 



of eggs of sponges;^ Berthold^ clearly described it for the 

 &gg of the sea-urchin as an unmistakable consequence of 

 sperm-contact with egg. A year later O. and R. Hertwig 

 suggested that eggs are endowed with contractility.^ The 

 earliest description known to me of contraction in the ecto- 

 plasm is that given by Ransom in 1854 who very clearly 

 described it as a consequence of insemination, a work which 

 has not received the attention it merits.'' 



That contractility is inherent in the ectoplasm of eggs 

 can be readily demonstrated. Unfertilized Arbacia-eggs, 

 for example, may be drawn out into long tenuous strands 

 by putting them among fibres of lens paper. Since 

 in this egg when it is unfertilized the endoplasm is highly 

 fluid, this elasticity is due to the ectoplasm (including the 

 vitelline membrane). The normal contour is readily 

 regained without loss of fertilization-capacity. Paramoecia 

 likewise can squeeze themselves through fine tubes and 

 assume most bizarre shapes, returning again to the normal 

 appearance when the pressure is released.^ Lillie,^ speaking 

 of the egg of Chaetopterus, says: "The protoplasm of this 

 egg is much more fluid than that of any other egg I have 

 tested; in consequence, the egg elongates even with rela- 

 tively low centrifugal force." And later "The egg is an 

 elastic sphere; it therefore elongates in the direction of 

 centrifugal force."'' I conclude from these statements that 

 the elasticity of this egg is due to its surface. Mrs. 

 Andrews^ attributes elasticity of cells to the ectoplasm. 



1 Metschnikoff, iSjg. 



- Berthold, I.e. 



■■' Hertwig, 0. and R., /SS/. 



■* Ransom, I.e. 



5 Just, igzSc. 



^ Lillie, F. R., igoS. 



^ Ibid., p. 72. 



^ Mrs. Andrews, iSgy. 



117 



