
456 THE AMERICAN NATURALIST.  [Vou. XXXVI. 
regards it as probable that similar masses constitute the anlages 
of the superficial buds known to occur in some hexactinellids 
(Rhabdocalyptus, Lophocalyx). 
In two other species what appears to be the complete intra- 
parental history of the archaeocyte congeries was made out. 
But before describing Ijima’s observations on these forms I 
wish to digress and point out how much commoner archzocyte 
_masses seem to be in the Hexactinellida than ova and sperm. 
Ijima recalls the fact that very little is known concerning 
the ova and spermatozoa of these sponges. Schulze (80, '87) 
describes sperm masses and ova (0.3 mm. in diameter) as pres- 
ent in more or less abundance, and usually in the same indi- 
vidual, in Euplectella aspergillum. Schulze was never able to 
discover any distinct segmentation stages. Ijima himself says: 
* [t is somewhat surprising to me that, although the different 
hexactinellid species histologically studied by me are not few 
in number, yet scarcely a single case in which either of the 
sexual products was indisputably developed came under my 
observation." As regards the male elements Ijima says he 
is quite in the dark, that he has never seen spermatozoa or 
indisputable sperm masses, nor indeed does he feel disposed 
to say that he has seen ova. In one specimen of Euplectella 
marshalli a number of cells were observed, the larger ones 
measuring IO-I5 4, sometimes 23 p, in diameter. Such cells 
are connected by transitional stages with, and are undoubtedly 
derived from, archzocytes. Ijima thinks these cells are young 
stages in the development of bodies similar to those described 
by Schulze as ova in Euplectella aspergillum, but does not 
commit himself to the view that they are eggs. In another 
sponge, a specimen of Leucopsacus, comparatively large spher- 
ical or ovoid cells, 20-40 p in diameter, were found in some 
abundance. Such cells were not connected by transitional 
stages with archzocytes, and the describer again does not find 
the evidence for their ovum nature absolutely convincing. 
The fact that Ijima found no indubitable sexual elements is 
the more surprising since in the case of Euplectella marshalli 
he made special search for them, examining numerous speci- 
pm collected xus the four seasons of the year. The rarity 
