HEXACTINELLIDA. 



I. INTRODUCTION. 



In this Report the HexactineUida collected during the Albatross cruises 

 of 1899-1900 and 1904-1905 in the Tropical Pacific under the direction of 

 Alexander Agassiz are described. 



Mr. Agassiz's hberality has enabled me to employ methods of research and 

 graphic representation not hitherto used and to describe the material very 

 fully. 



• II. METHODS. 



1. The soft parts. 



The deep-sea HexactineUida which come into the hands of specialists are 

 generally in such a condition that very Uttle can be made out, by the ordinary 

 methods of sectioning and staining, of their very tender soft parts. Tliis is 

 due to their mixing with the deep-sea ooze during the passage of the dredge 

 over the bottom and to the pull and pressure acting on them in the long haul 

 to the surface. After many experiments I finally found the following method 

 best suited to this kind of material: — a piece of the specimen, I to 1 cm. in 

 diameter, with intact surface is imbedded in paraffin and cut into thick radial 

 sections. These are not stuck on the sUde but placed free, first in xylol, then in 

 alcohol, where much of the deep-sea ooze, which has got into the sponge during 

 capture, and many of the fragments of spicules spUntered in cutting fall out of 

 the section, so that it becomes fairly clean. These loose sections are then 



