248 whitman: ' [Vol. I. 



tion of the Lamprey egg, as described by A. Muller (24) and by 

 Kupfifer and Benecke (20). The micropylar area is represented 

 by a watchglass-shaped segment of the egg membrane, and is 

 surmounted by a prominent hyaline dome, which here replaces 

 the mucous envelope ( " Schleimhiille "). 



The first point which is of special interest in the description 

 is the fact that the spermatozoa wJiicJi come in contact with the 

 mucous envelope do not try to penetrate it, while those which reach 

 the dome (Miiller's " Flocke") immediately take a direction radial 

 to the " watch-glass.'^ The whole dome becomes so thickly 

 beset with spermatozoa that it presents the " picture of a 

 beard." A. Miiller likened the appearance to that of iron filings 

 arranged in a feathery tuft around the end of a magnet, and 

 the comparison is fully indorsed by Kupffer and Benecke. The 

 whole account impresses one very strongly with the fact that 

 attraction is felt before contact with the vitellus, and that its 

 influence is strongest at, possibly confined to, the micropylar 

 area. 



With reference to this point, Kupffer and Benecke remark: 

 "Themicropyle is, therefore, not an open passage, as it would ap- 

 pear to be from the statements and figures of Calberla, but merely 

 a more permeable place. But it remains a mystery how this 

 point is always hit by a zoosperm, unless one is permitted to as- 

 sume that the interaction between egg and ^oosperms is more 

 energetic in that radius which passes through the micropyle than 

 in any of the other radii'' (p. 15). 



The attraction manifests itself not only in the behavior of the 

 spermatozoa, but also in a contraction of the egg, which shows 

 itself in the ring-like space left between the rim of the "watch- 

 glass " and the vitellus. A single spermatozoon, after it has 

 penetrated the dome and placed itself in a position radial to the 

 micropylar surface, is sufficient to induce the immediate retrac- 

 tion of the vitellus ; but the intensity of this action increases with 

 the number of spermatozoa. Kupffer and Benecke justly in- 

 fer, therefore, " dass die Zurilckziehung des Dottcrs nicht auf 

 einer Contactwirkung, sondern aif einer Fernwirkung dcr radilir 

 gcord7ieten Zoospermien bcrulit" (p. ii). 



The second point of interest is the fact that all imdulations 



24. Aug. Muller. Beobachtungen ii. d. Befruchtungserscheinungen im Ei d. 

 Neunaugen. Vcrhandl. d. Konigsberger phys.-oconomischen Geselhchaft, 1864. 



