1 9 2 o] SEIFRIZ—PRO TOP LA SM 375 



Marine ova 



The fully mature, normally discharged eggs of Fucus are 

 decidedly viscous (v.v. 6). The unripe eggs are of lower viscosity. 

 The properties and behavior of the ova of Echinar achnius and 

 Tripneustes are so similar that they can be considered together. 



mature 



Trip 



ova, but barely of very viscous consistency (v. v. 7). Kite has 



asm 



gel." Chambers (5) calls attention to the fact that Kite's 

 paper "is a pioneer one in microdissection research. The observa- 

 tions recorded were necessarily fragmentary." Kite was probably 

 dealing with degenerate gelated protoplasm, or else he fully appreci- 



asm 



term 



gel. Chambers (6) states that "the interior cytoplasm of a 

 marine egg is a viscous fluid. The viscosity is high enough to 

 prevent any Brownian movement of the inclosed granules." 

 Since the expression "viscous fluid" holds no place in a scale of 

 viscosity, nor is it compared with any other commonly known 

 substance, it is not quite clear just how viscous is the living viscous 

 fluid of a marine egg. The minimum viscosity which the absence 

 of Brownian movement (a criterion used by Chambers) will per- 

 mit is apparently the viscosity of concentrated laboratory gly- 

 cerine. Exner, according to Lehman (16), found that "the 

 concentration of ordinary commercial glycerine (specific gravity 

 1. 21) was just enough to put a complete stop to the vibration." 

 A very slight dilution of concentrated glycerine (specific gravity 

 1 . 25) is sufficient to permit a noticeable Brownian movement of 

 suspended carmine particles. If Brownian movement is impos- 

 sible in a very viscous substance such as glycerine, which has a 

 viscosity value of 7, then protoplasm in which no Brownian move- 

 ment is evident must apparently possess a consistency of about 

 this value. It is such a viscosity value (between 6 and 7) which 

 I attribute to echinoderm ova. 



