NARRATIVE OF THE CKUI8E. 



439 



methods (often newly devised for this special purpose) and instruments was it possible to 

 arrive at a clear understanding as to the minute structure of the indifferently preserved 

 specimens. Obviously just those portions have caused the most trouble which were the 

 worst preserved, or only came to hand in small fragments. 



Fiq. 161. — Poliopogon amadou, Wyv. Thorns., a representative of the Hyalonematida*. One-third the natural size. 

 Attached to branches of Corattium (see p. 125). 



" As a rule small pieces selected from various regions of the sponge were first soaked for 

 some time in concentrated hydrochloric acid and then boiled in it for a few minutes, 

 washed out with water and alcohol, dehydrated by alcohol of increasing strength, cleared 

 by oil of cloves, and finally after teasing and careful spreading out mounted in Canada 

 balsam. In this manner the isolated siliceous spicules and the small fragments of con- 



