VITKOLLUIA FEßTILIS. 45 



are very conspicuous on stained preparations on account of their 

 compactly packed elements being very deeply colored (seen in 

 PL III., figs. 8-10 as deep blackisli spots). Though they may 

 take a somewhat irregular shape in accordance with the circum- 

 stances of the space occupied by them, the normal shape of the 

 congeries after attaining a certain size seems to be spherical (figs. 

 13-15). A rather small congeries of 40 /^ diameter (flg. 13) is 

 already evenly delimited on the external surface, though evident- 

 ly it is still without a special enveloping membrane or epithel- 

 ium. It may grow to doul)le or more than double that diame- 

 ter without showing a morphological change, except of course in 

 the numerical increase of the closely crowded cells. The sharj)- 

 ly defined surface pregses against the incurrent side of the walls 

 of the chambers, right in the midst of which the body is situat- 

 ed. The extent of the chamber-wall surface in contact with this 

 is such that inceptively several little groups of archseocy tes might 

 have taken origin on it ; hence it is exceedingly probable that 

 the growth of an arclueocyte-congeries takes place not only by 

 multiplication of its elements but also by fusion of originally 

 separate groups. 



The archgeocytes, taken singly, are only 2-4 l^ large. PL 

 III., Fig. 12, which shows a small group of them as seen in a 

 borax-carmine pi'eparation, is not a good representation in that it 

 fails to indicate the nuclear outline in each cell-l)ody. A reviewed 

 examination of the ^^réparations, long after the plate had 

 been printed, Ijrought me to the conviction that here, as I be- 

 lieve in Hexactinellidan archœocytes generally, there exists a 

 greater or less quantity of cytoplasm around the nucleus, — in 

 other words, that we have here to do with small entire cells and 

 not with free nuclei {cfr. Contrib. L, pp. 158, 171). The 



