1897J MICROSCOPICAL JOURNAL 183 



ent lines, yet arriving at the same results, commend 

 themselves as conclusive. Nor can we forget the emin- 

 ent services on diatom structure rendered by our Secre- 

 tary, Mr. Karop, associated with further ideas on their 

 development. But the diatom will never cease to be of 

 primary importance to the microscopist, as the abundance 

 and variety of its forms even exhaust our imagination, 

 and the volumes written upon it, though numerous, seem 

 to be only forerunners of more to come. 



I have alluded to the movements which were once 

 thought to be one of the reasons to indicate animal life, 

 as seen in the Naviculacea) ; but in these forms it is by 

 no means so remarkable as in one less commonly met 

 with, viz., the Bacillaria paradoxa, wherein a number of 

 parallel rods slide out side by side on each other, in 

 a manner so curious as to challenge all hypotheses to 

 clearly explain them to us. 



But movement can in no way of itself be recognised as 

 a distinction of animal nature, and many examples of the 

 Algae, notably that of Volvox globator, go far beyond 

 what is seen in any of the Diatomaceae, and sometimes 

 there is a lingering of opinion here, as to which order 

 the latter should belong. Hesitation of this kind has its 

 value, as it directs attention to the subject, and, finally 

 to a decision. Sponges are now relegated to the animal 

 kingdom, but it is singular that doubts on this should 

 have belonged to modern science; for Pliny, who wrote 

 at the beginning of the Christian era, in his curious com- 

 pilation, entitled "Natural History," distinctly saw the 

 true place they should occupy. 



One might quote eminent names near to our ov/n time 

 who have taken a different view, and it is remarkable, 

 that one of such large experience as the late Dr. Gray, of 

 the British Museum, should have been once on this side 

 and considered the spicules the analogues of the hairs of 

 plants. This comes out in a passage of arms between 



