British Association. 4069 



with Dr. Lankester that the best expression to be found for animal and vegetable life 

 at present was, the general fact of vegetable tissue giving off oxygen gas and absorb- 

 ing carbonic acid, whilst animal tissue absorbed oxygen and gave off carbonic acid. 



" On the Morphology of the Pycnogonidae, and Remarks on the Development of 

 the Ova in some Species of Isopodous and Amphipodous Crustacea," by Spence Bate. 

 The paper was read by Dr. Lankester, who also exhibited a series of drawings, made 

 by Mr. Bate, of the more minute forms of Crustacea, and stated that the Committee 

 had requested Mr. Bate to draw up a report on the present state of our knowledge of 

 the lower forms of Crustacea, which would, he hoped, be presented at the next Meet- 

 ing of the Association. He also expressed a wish from Mr. Bate to have sent to him 

 any specimens or information that might be in the possession of naturalists in other 

 parts of the country. 



Prof. Allman drew attention to the analogies between the conditions of develop- 

 ment in the Crustacea and Arachnida. Mr. Bate found but six legs amongst these 

 lower Crustacea, and this was the case with some forms of Arachnida, more especially 

 the Acaridae. 



Mr. J. D. Sollitt read a paper, prepared by himself, in conjunction with Mr. R. 

 Harrison, " On the Diatomaceae found in the Vicinity of Hull," showing that the fresh- 

 water and marine Diatomaceae were exceedingly numerous in this locality; the beauty 

 of the varied forms of which were such as to delight the microscopist, and, at the same 

 time, some of them are highly useful as forming that class of test objects for micro- 

 scopes which are the best calculated of all others for determining the excellence and 

 powers of object-glasses. As test objects they were first discovered by the Hull micro- 

 scopists, and have now been adopted as such by all the microscopists not only in this 

 but in all other countries. Mr. Harrison and Mr, Sollitt discovered the markings on 

 those delicate siliceous coverings as early as 1841. It was shown that the markings 

 on those shells were so fine as to range between 34,000 to 130,000 to the inch ; the 

 Plurosigma strigilis being the strongest marked, and the Navicula Acus the finest. Tt 

 was afterwards pointed out that a large bed of fossil fresh-water Diatomaceae, of at 

 least two feet in thickness, had been discovered in Holderness, and that in a sub- 

 merged forest on the coast of Holderness numbers of fossil fresh-water Diatomaceae 

 had been discovered, although the sea flows over the part at every tide. The paper 

 concluded by pointing out that upwards of 150 species of marine and fresh-water Dia- 

 tomaceae had been identified in the neighbourhood of Hull. 



The reading of this paper was followed by a long discussion. 1. In relation to the 

 microscopic powers and the structure of the instruments employed by the Hull ob- 

 servers. 2. With regard to the nature of the lines found on the surface of the Diato- 

 maceae. 3. 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 Natchet's manu- 

 facture, the one-sixteenth and the one-eighth of an inch focal distance, with angles of 

 aperture of 115° and 105 p diameter, and for the larger markings Smith's one-fourth, 

 with an aperture of 46°. With these glasses they had detected markings whose inter- 

 spaces 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. Wal- 

 ker-Arnott considered that these curious beings must now be regarded as plants. Prof. 

 Allman looked upon them as the starting-point of Nature, in which the mineral, ani- 

 mal, and vegetable laws of creation were struggling for ascendancy. Mr. Sollitt and 



