MIDLAND NATURALIST. A Ve 33 
a bag made of netting can be used advantagously in bringing them 
up from timber as piles driven into the rivers near dams etc. Some- 
times a mill race is emptied for repairs or a reservoir of water works 
for the purpose of cleaning, and then is the time to search for 
sponges among the rocks and timber. 
Always collect them preferably from timber as they can more 
easily be removed by slicing off chips or splinters and they are 
secured without too much injury. The gemmules which are deep 
within will not be lost. 
Young sponges such as are collected late in Spring or early in 
Summer will not have gemmules and, although useful to collect at 
all seasons, yet if for the purpose of determining the genus and 
species they must be collected not earlier than July. If the 
student’s purpose is only to gather them as a collector, then he may 
transfer them directly into 50 per cent. alcohol or better 35 per cent. 
and when he gets home after some hours transfer them to stronger 
alcohol. Others may be placed in shady places to dry, and to pre- 
vent decay, they should be turned over at short intervals. In no 
case should they be left in water for any length of time as they will 
rapidly decay. If one wishes to study their life action they must 
be transferred as quickly as possible to shallow glass dishes. To 
demonstrate the circulation of water through the sponge mass a 
solution of carmine is made in pure water. After having placed 
the fresh living sponge into a suitable dish and covered well with 
water a small amount of the carmine solution is taken up with the 
. pipette and gently emptied over one part of the sponge—soon the 
carmine colored, water will be seen to disappear into the mass drawn 
in by a suction movement, and shortly after the carmine colored 
water will be seen to be ejected like diminutive clouds from minute 
chimney-like structures. This circulation is caused by the flagel- 
lated cells that line the canals in the mass. One can also watch 
the development of the gemmules by securing eight or ten of them 
and place them in a shallow watch glass with water, and cover them 
with a piece of glass to prevent evaporation—should this take place 
to some extent, one can easily add with a pipette very gently some 
pure water. 'The watch glass is placed near a window not too 
much lighted, and in a few days the growth can be examined under 
a compound microscope with a three-quarter inch lens, or with a 
water immersion lens of a higher power. 
The student may take some of the fresh material and place a 
bit of it on a slide and examine it, but he will find that a bit of 
thoroughly dried material mounted directly into Canada balsam 
4 
