266 WATASE. [Vol. IV. 



figure in the blastoderm of the squid. Fig. VI shows the same 

 in a more advanced condition, as seen in the developing ovum 

 of a starfish {Asterias vulgaris) common at Wood's Holl. The 

 latter was brought out by the application of the method recom- 

 mended by Boveri in his recent paper.^ The figure shows a 

 striking resemblance to those given by Agassiz and Whitman ^ 

 in their recent work on the development of the osseous fishes. 



The figure consists of two essential anatomical features, (i) 

 the central, elliptical body, and (2) the two star-like, radiating 

 structures. The former corresponds to the outline of the origi- 

 nal nucleus, as will be shown later, and the latter constitute the 

 asters of Fol, spheres attractives of van Beneden, or, to use a 

 more recent nomenclature, the arcJioplasmic spJieres of Boveri. 

 The central area of archoplasm {A) is situated in the substance 

 of the cytoplasm (C). From the granular archoplasmic substance 

 as a centre, there radiate out in all directions a large number of 

 fibre -like rays, the arcJioplasmic filame^its {B) and {E). A por- 

 tion of these ray-fibres penetrate into the elliptical part of the 

 figure, and constitute the intra-Jiiiclear arcJioplasmic filaments 

 {E) ; while those lying outside of the elliptical body are the 

 extra-miclear arcJioplasmic filaments {B). 



The elliptical portion of the figure consists of three parts, two 

 terminal and one intermediate. The terminal portion, which 

 presents different optical properties from the intermediate part, 

 consists of a hemispherical mass of a slightly stainable, semi- 

 liquid substance, which I believe to be the nuclear sap of the 

 original nucleus. Into this part the archoplasmic rays extend, 

 as has already been mentioned. The two terminal masses of 

 stainable substance are separated from the intermediate non- 

 stainable bundle of filaments by parallel chromatic "plates " (;/), 

 {n), — the cJiromosomes (Waldeyer) of the original nucleus. The 

 non-stainable intermediate filaments above referred to are the 

 interzonal arcJioplasmic filaments {D), • — " interzonal filaments " 

 of Mark, "filaments reunissants " of van Beneden, "gubernacu- 

 lum " of Maupas, " Verbindungschlauch " of Strasburger, "con- 

 nective filaments," " Verbindungsfaden," etc., of authors. 



One plate of chromosomes goes to one daughter nucleus, and 



^ Zellen Sludien, III, pp. 6, 7, 1S90. 



2 Agassiz and Whitman : Memoirs of the Museum oj Comparative Zoology at 

 Harvard College, Vol. XIV, No. i, 18S9. 



