338 the president's address. 



bulbs. It was thought that a similar material would be 

 similarly affected by the action of light, and thus would 

 prove, or tend to prove, the true construction of the valve. In 

 the theory of elevations, it is not so long ago that arrangements 

 were made in side illuminations by a pencil of light, thus sup- 

 posing to give a true and artistic light and shade. But, in both 

 these experiments, it seemed to be forgotten that they were 

 begun in a foregone conclusion ; and, as I have previously said, 

 you naturally, in such a case, see what you wish to see. Cer- 

 tain accidents, fractures, and peculiarities inconsistent with the 

 above-named views, assisted by careful illumination, seem now 

 to have tolerably settled the question to be on the side of 

 apertures, and my predecessor has worked most successfully 

 thereto. That this must be the general consent on such mark- 

 ings throughout the Diatomacea? must probably be entertained, 

 though it would be dangerous to affirm that there was no varia- 

 tion from it in the multiform changes of nature. 



But the subject has been so admirably worked out and 

 recorded by two papers in our Journal, one by Mr. C. Haughton 

 Gill, April, 1890, in which he has well described his mode of 

 preparation of the objects wherewith to determine the structure. 

 Another by Mr. Nelson, in May, 1891, goes into the same matter 

 by the use of high powers, and these papers, showing a working 

 on different lines, yet arriving at the same result, commend 

 themselves to us as conclusive. Nor can we forget the eminent 

 services on diatom structure rendered by our Secretary, 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 

 Naviculaceae ; but in these forms it is by no means so remark- 

 able as in one less commonly met with, viz., the Barilla ria 

 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 



