1108 



strigilis being the strongest marked, and the Navicula Aciis the finest. 

 It was afterwards pointed out that a large bed of fossil freshwater Dia- 

 toraaceae, of at least two feet in thickness, had been discovered in 

 Holderness, — and that in a submerged forest on the coast of Holder- 

 ness numbers of fossil freshwater Diatomaceae had been discovered, 

 although the sea flows over the part at every tide. The paper con- 

 cluded by pointing out that upwards of 150 species of marine and fresh- 

 water Diatomaceae had been identified in the neighbourhood of Hull. 



The reading of this paper was followed by a long discussion. First, 

 in relation to the microscopic powers and the structure of the instru- 

 ments employed by the Hull observers. Secondly, with regard to the 

 nature of the lines found on the surface of the Diatomaceae. Thirdly, 

 on the question of the vegetable or animal nature of the Diatomaceae. 

 From the statement of Mr. Sollitt and Mr. Harrison, it appeared that 

 the lenses which they had employed for the minuter markings were 

 object-glasses of Nachet's manufacture, the one-sixteenth and the 

 one-eighth of an inch focal distance, with angles of aperture of 115° 

 and 105° diameter, and for the larger markings one-fourth of Smith's, 

 with an aperture of 46°. With these glasses they had detected mark- 

 ings whose interspaces numbered 130,000 to the inch. Mr. Sollitt 

 regarded the lines as consisting of rows of minute tubercles, which 

 gave the appearance of continuous lines. 



Dr. Walker-Arnott considered that these curious beings must now 

 be regarded as plants. 



Prof. Allraan looked upon them as the starting-point of Nature in 

 which the mineral, animal, and vegetable laws of creation were strug- 

 gling for ascendancy. 



Mr. Sollitt and Mr. Harrison regarded them as animals, and quoted 

 the opinion of Prof Bailey of New York, 



Prof Balfour referred to their resemblance to Desmideae, and the 

 conjugation observed amongst them as conclusive proofs of their rela- 

 tion to the Confervae, whose vegetable nature no one doubted. 



Dr. Lankester referred to Schleiden's objection, of their possessing 

 a highly complicated structure, and pointed out their resemblance to 

 the Foraminifera, which all agreed to be animals. It had, however, 

 been asserted that the Diatomaceae possessed starch, and as yet this 

 had not been discovered as a secreted product in beings recognized 

 as truly animals, whilst starch was universally present in true vege- 

 table productions. 



