498 THE AM ERIC AX NATURALIST. [Vol. XXXVIII. 



he Ovum of Dcsvunrnathns fuwa William 

 A. Hilton, Cornell University. — During- 

 the last few years several amphibian eggs 

 have been found which, from the few stages 

 of development described, seem to indicate 

 a meroblastic rather than a holoblastic 

 method of cleavage. The first of these 

 F.o , -Surface view of a ""^^^ Tcportcd by H. H. Wilder (1899) for 

 four- cell stage fron, above Dcsmognathus, thc second for Autodax, 

 by Ritter and Miller, also 1899, and the 

 third by Montgomery for Plethodon in 1901. In all of these 

 forms only the later stages were observed. 



As Desmognathus is very abundant in 

 centra] New York, advantage was taken of 

 the opportunity for a thorough investigation 

 of the earlier stages. 



The eggs are about 3.5 mm. in diameter 

 and entirely devoid of pigment. The general "e,,' ~ gf'/and 2 ^fi'j^'t 

 appearance is creamy white except at the and second division 

 animal pole, which is chalky white. In this pi^^es (about x 8). 



chalky white area "the first division furrows 

 make their appearance. The first and sec- 

 ond furrows are at right angles (Fig. i), 

 but soon these lose this geometrical regu- 

 larity and the later division lines may be 



In the four-cell stage the first cleavage 

 plane has cut somewhat deeper than the 

 second, but neither has yet cut deeply into 

 the central mass of yolk {Fig. 2). In the 



slight 



