OXNEEELLA MARLTIMA. 
531 
thus established, it became obvious that at least one function 
of this organ is skeletal ; it serves as a central point of 
attachment, or focus, for the axial fibres of the radiating 
pseudopodia. But whether the centroplast possessed any 
other function was not apparent from its morphological 
relations, and had, therefore, still to be proved. 
About a quarter of a century ago, the centrosome, then 
recently discovered by E. van Beneden, was occupying the 
.attention of most cytologists. If an Acanthocy stis is 
homologous Avith a metazoan cell — as it was generally sup- 
posed to be — and its nucleus homologous with the cell’s 
nucleus ; then if the centrosome is a permanent organ in the 
cell — as was also then generally believed — there ought clearly 
to be some corresponding organ in the Acanthocystis. 
And seemingly there was : there was the centroplast, already 
described and figured exactly like a centrosome. It was 
therefore almost inevitable that someone should suggest 
that centrosome and centroplast are homologous struc- 
tures. 
So far as I am aware, the first suggestion of this homology 
to appear in print came from Biitschli (1892). It was, 
however, nothing more than a suggestion based upon the 
striking structural similarity of the two organs — a similarity 
Avhich is, as I shall try to show, somewhat misleading. 
At about this time a new fact was brought to light by 
Sassaki. Whilst studying a new lieliozoon (G-y mnosphsera 
albida), he disco\^ered that the division of the whole organ- 
ism is preceded by a division of the centroplast — a fact Avhich 
justified him, more than a mere structural resemblance could, 
in homologizing this organ with the centrosome of a metazoan 
cell. It should be noted that Sassaki’s observation had been 
made and written down by him in 1891, 1 although it was not 
published until 1894. To the Japanese zoologist, therefore, 
belongs the credit, not merely of first suggesting that the 
centroplast is the homologue of a centrosome, but of having 
1 See footnote to Sassaki’s paper (p. 45) by R. Hertwig. 
