
ON THE ASEXUAL ORIGIN OF THE CILIATED 
SPONGE LARVA. 
H. V. WILSON. 
IN 1891! and in 1894? I published certain observations which 
led me to believe that in monaxonid sponges free-swimming 
larvae identical in structure with those developing from eggs 
are in some species produced asexually. For one such species, 
Esperella fibrexilis Wilson, the observations referred to are 
in brief as follows: (1) Parenchymal cells well supplied 
with yolk granules are found collected together in abundant 
small groups of varying size. Such groups have no definite 
shape and may contain few cells or many, and the compo- 
nent cells may lie together very loosely or be packed pretty 
closely? The microscopic pictures indicate that the groups 
owe their origin to wandering cells that have collected together. 
(2) Rounded masses of similar cells are found, the cells tightly 
packed and polygonal in outline. To such masses, which are 
surrounded by a follicle composed of a single layer of flattened 
cells, I have applied the term “ gemmule.” The smaller gem- 
mules are regarded by me as arising from the amorphous masses 
of parenchymal cells above mentioned, and the microscopic pic- 
tures further indicate that the gemmules grow both by cell 
divisions and by fusion with one another. The gemmules vary 
greatly in size. The smallest show zz section only a few cells, 
the largest several hundred cells,* the diameter of the largest 
gemmules bearing to that of the smallest about the ratio of 
tentoone. With increasing size of the gemmule, the component 
1 Notes on the Development of Some Sponges, Journ. of Morph., vol. v, No. 3. 
? Observations on the Gemmule and Egg Development of Marine Sponges, 
Journ. of Morph., vol. ix, No. 3. 
3 Journ. of Morph., vol. ix, No. 3, Pl. XIV, Fig. 8; Pl. XV, Figs. 15-15. 
t Itid, Pl. XV, Fig. 9, 5 cells; Fig. 16, 18 cells; Fig. 11, 37 cells; Fig. 9, 
about 6o cells; Fig. 21, about 100 dte: Fig. 18, several hundred cells. 
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