I 9°7] 
Wilson — A New Method 
93 
the normal sponge. Whether in this regeneration the trans- 
formed and separated collar cells again unite to form the flag- 
ellated chambers, I can not say. I think it very doubtful. 
In the two classes of cases just described the sponge as a 
whole degenerates and slowly shrinks. Cellular death takes 
place so gradually that at no time is there any obvious corpse 
tissue or skeletal debris. Much more common and of far great- 
er interest are the following cases. In these a large part of 
the sponge body dies in the course of two or three weeks, 
leaving the skeletal network still in place and bearing the 
brown decaying remnants of the flesh, which, as maceration 
continues, are washed away. In places, however, the sponge 
body does not die. Here masses of living tissue are left, 
conspicuous amidst the dead remains by their bright 
color and smooth clean surface. These living fragments may 
be classified into three groups. First, the upper end of an as- 
cending* lobe or a considerable part of the body of the lobe may 
be left alive in its entirety, thus forming a more or less cylin- 
drical mass up to 5 mm. diameter, with a length sometimes 
two or three times the thickness. The histological condition 
of these masses is not very different from that of the sponges 
already described. Such a mass may be said to consist of an- 
astomosing trabeculae, separated by the remains of the canal 
system. The mesenchyme composing the trabeculae consists 
of discrete cells interconnected by processes to form a syncti- 
um. The flagellated chambers as such have nearly disap- 
peared, although remnants may still be recognized. In them 
the collar cells have transformed into simple polyhedral bodies 
that are widely separated. The bulk of the chambers have 
broken up into their constituent cells, and these are now scat- 
tered as elementary parts of the general mesenchyme. When 
such masses are attached to wire gauze and hung in a float- 
ing live-box they transform into perfect sponges. 
A second class of surviving remnants includes masses scat- 
tered over the general surface of the sponge. These may be 
spheroidal and small, less than one millimeter in diameter. 
Usually they are flattened and of an irregular shape with 
