A Laboratory Guide for an Elementary Course in General Biology

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ... CHAPTER XI. A SPONGE Grantia ciliata). THIS sponge is found abundantly on the Northern Atlantic coast north of Vineyard Sound, in clusters of small cylindrical individuals not over an inch in length. These should be collected and preserved in alcohol for use. Morphology.--With a simple lens examine one of the sponges for the following points, viz: --I. The cylindrical external form of the sponge body, by one end of which it is attached. Note: --1. The outer surface is beset with numerous needle like bodies called spicules. 2. At the free end there is a circle or crown of longer spicules. 3. Within the circle is an opening, called the osculum, leading to a central cavity or cloaca. The body is therefore a hollow cylinder or tube closed at the lower end but open at its free end. 4. At the base may be found buds which represent new sponge bodies in process of formation. II. By tearing the sponge apart carefully with needles the structure can be still more minutely studied, and the following discerned, viz: --1. The framework of spicules which supports the sponge flesh is composed of numerous hard spicules of which the external spicules mentioned above are the protruding portions. a. Boil a portion of the sponge in a test tube of solution of caustic potash. Take a drop of the sediment from this solution and examine it with a high power of the microscope. It will be found to consist of minute spicules of various forms which should be carefully studied and sketched. b. Carefully wash a portion of the sediment in water and pour upon a little acid. The effervescence is due to the setting free of carbon-dioxide. The spicule is composed of carbonate of lime, which is decomposed by the acid. The spicule soon disappears. 2. On the inner surface of the