1 6 Laboratory Guide in Zoology 



,the high power the margins of the sponge. You are 

 likely first to see great numbers of very small, round, 

 greenish cells ; these are a species of one-celled alga — 

 a microscopic plant — which develops in connection with 

 the sponge. Notice, also, certain much larger, spheri- 

 cal, granular cells, having somewhat the appearance of 

 a resting Amoeba. Imbedded in the protoplasm of 

 these cells, there are likely to be many of the micro- 

 scopic algae just mentioned. These larger cells are 

 the ones that form the sponge " flesh." Some of them 

 are likely to show movements similar to those of the 

 Amoeba, and in consequence they are called amoeboid 

 cells. Make drawings of one or more of them. 



IV. — Examine the margin of the particle of sponge : 

 notice the soft cells connected with the whitish, needle- 

 like spicules. 



V. — Place a small piece of sponge in caustic potash in a 



watch glass for an hour, then study the spicules under 

 the microscope, after they have become separated from 

 the tissues. Make drawings of three or four of them. 



VI. — Sponges collected during autumn and winter are 

 likely to show peculiar yellowish spherical gemmules 

 in the body. These are reproductive bodies by means 

 of which the sponge passes through the winter. 



THE SIMPLE MARINE SPONGE 



(grantia SP.) 



This sponge is a marine animal, found commonly along 

 the Atlantic coast of the United States. 



I. — Make a careful drawing of your specimen as seen 

 through a hand lens of low power. Show in the 

 drawing these parts : — 



