1878.] 



Phyto-Palceontological Investigations, 



223 



water ; the stone will thns be raised to a higher temperature and again 

 exposed to the soaking process. The ice formation and the soaking 

 being thus employed alternately, the widening of the splits increases, 

 till at last the stone opens of itself exactly along the enclosed fossil, 

 which then comes to the light of day uninjured and in the best state of 

 preservation. 



This method offers not only the advantage of securing for investiga- 

 tion the most complete and well preserved fossil plants, but it yields 

 also a much larger amount of material than could be obtained by the 

 old method of forcibly splitting with a hammer. In this way no fossil 

 can be lost. All the fossil plants in the stones are uninjured. Luck 

 and chance are excluded. To obtain an abundant supply of useful 

 material for investigation is of the greatest importance for the study 

 of Phyto-Palaeontology and must lead to better and surer results. 



II. — Method of Investigating Fossil Hants. 



Phyto-Palasontologists have hitherto made too many species. Un- 

 fortunately authors have been too readily disposed to adopt as a new 

 species every slightly differing form. Consequently not only is science 

 encumbered by a useless burden, but it is itself brought into a discredit 

 which has occasioned serious injury to the progress of this branch of 

 science. The most important way of remedying this evil, lies in 

 procuring abundant material for investigation, showing a series of 

 forms, and thus causing the false species to disappear. A collection 

 of fossil plants acquired by careful study must therefore contain not only 

 rare specimens, but as large a number as possible of a series of forms of 

 common fossils. These series should be divided into two groups, the 

 series of the contemporaneous, and of the non-contemporaneous 

 (genetic) forms. The first is obtained by the bringing together the 

 forms of a fossil out of the extension of one and the same layer 

 (horizontal extension), the second in the searching for a fossil in 

 different horizons (vertical extension). The latter series supplies the 

 material for the phylogeny of the species, the complete elucidation 

 of which is of the highest importance for the history of the develop- 

 ment of the vegetable world. 



A second way of removing the above-mentioned unsatisfactory state 

 of things would be to put aside certain obsolete notions and prejudices. 

 People are prone to admit mere differences of stratigraphical position as 

 sufficient ground for the acceptance of a particular species, when indeed 

 there appears to be no substantial reason arising out of its distinctive 

 character. Only too often an insignificant difference of form, then re- 

 garded as important, is held to justify the acceptance of a species, if the 

 fossil belongs to another horizon or another formation. My experience, 

 however, has led me to the conclusion, that, in many cases, one species 

 passes through many horizons and indeed through greater periods, 



