Dr. F. A. Bather— Prof. Nathorsfs Studies of Fossil Plants. 459 



at the margins, and were surrounded by microspores that had separated 

 from them. On teasing the ground-mass with the dissecting-needle, 

 microspores appeared in countless numbers: the ground-mass was 

 entirely composed of them, and the addition of ammonia broke it up 

 into these constituents. These microspores are so thin that they can 

 scarcely be seen if preserved in glycerine-jelly or Canada balsam, 

 especially when they have been rendered more transparent by 

 ammonia. Fortunately they can be stained with erythrosin, and this 

 renders their outline very sharp and clear, so that it has been possible 

 to reproduce microphotographs up to an enlargement of 750 diameters. 



The pollen-grains of fossil gymnosperms also may be obtained by 

 this method, and Professor Nathorst has studied the pollen-sacs of 

 a fossil hitherto supposed to represent the male flowers of Baiera 

 Muensteriana, but now described by him as AnthoUthus ^ Zeilleri, n.sp. 

 The two very small specimens, contained in a soft fissile shale of 

 Rhsetic age, were first treated with nitric acid alone, afterwards with 

 the addition of chlorate of potash, and it was soon seen that other frag- 

 ments were present. On isolating these their form appeared quite 

 different from that of Baiera, a fact that could not possibly have been 

 distinguished otherwise. An unopened pollen-sac was treated in the 

 same way as the sporangia mentioned above, and showed itself to be 

 quite full of pollen-grains of oval shape and from 36 to 48 /t in length. 



The indestructibility of spores and pollen-grains rendered it probable 

 that they could be washed out of Mesozoic clay deposits, in the same 

 way as plant-remains are washed out of Quaternary clays and sands 

 (see ISTathorst, Eihang Sv. Vet.-Akad. Handl., xvii, Afd. iii, No. 5, 

 1892; and G. Andersson, Geol. Foren. i Stockholm Forhandl., xiv, 

 1892). An experiment was therefore made with a certain Lias clay, 

 found at Hor in Scania, and full of plants preserved as they grew, 

 among which may be specially mentioned Clathropteris meniscioides, 

 Bictyophyllum Nilssoni, and Marattia horensis. A piece of this clay 

 was taken and washed after treatment with nitric acid. Though of 

 only some four or five cubic centimetres, it yielded an enormous 

 quantity of different plant-remains. Besides the larger fragments, 

 about fifty preparations of the finest mud were obtained, all con- 

 taining hundreds of spores or pollen-grains, and yet not half the mud 

 was used up. Obviously the clay was crammed full of such remains, 

 and among them the tiny spores of Marattiacese predominated. Other 

 forms could be referred with much probability to Dictijophyllum and 

 Clathropteris. The most interesting occurrence, perhaps, was that of 

 winged pollen-grains closely resembling those of Finns (sensu lato), 

 a genus previously unknown in rocks older than the Upper Rhsetic 

 of Scania. 



There seems no reason to doubt that fruitful results would accrue 

 from the extension of this research to other plant-bearing clays, no 

 matter what their age. 



1 The name AnthoUthus, originally used by Linne in Syst. Nat., ed. xii, as a 

 designation for ' Fhytolithus floris,'' is here adopted by Professor Nathorst as 

 a general term for all fossil flowers. It implies that the systematic position of the 

 species cannot yet be determined. Compare the use of the words Radiolus, Ent^-ochus, 

 and Cystis in Echinology. 



