128 The Botanical Gazette. [Mareh, 
such structures in the male pronucleus. Hence he thinks 
there can be no “quadrille of the centers.” Wilson até 
Mathews? in their investigation on the echinoderm egg also | 
tend to disprove the “‘quadrille of the centers.” 
Mead? studied maturation and fecundation in Chaetopte™ 
pergamentaceus. He traces the archoplasm and centrosom® 
of the segmentation nucleus from the male pronucleus, and | 
observations as in the conclusions drawn. And it should ‘i 
orne in mind that mere negative results of observation P “ 
or disprove nothing. As Strasburger has indicated ™ bs 
‘‘Neue Untersuchungen,” in regard to the invisibility of 
nucleus in the ripe pollen-grain of many dicotyledons ¥ 
ar stains, the invisibility ot ! | 
cleus in such cases must not be interpreted as indicating d 
absence of a nucleus, but much rather that the methods 
tae ae 4 the Ng terior in the fertilized egg of Mysostomé gla 
2 a . or . Rey aoe: : 
iyetes fertilization, tie in the echinoderm egg- New M6 
ont . quadrille m1 the centers, Jour. Morph. 10: 319. 1895. yer 
; ons On maturati d > P Chaetopterus | 
mentaceus Cuvier. Jour. Morph. 10: as. = Ss 
