224 Mr. Masters y on the Relation between the [March 16, 



systems, and the humblest plants have no others. All plants, but 

 Thallogeus, possess in addition a fibro-vascular system, and an axis, co- 

 existent with which is the presence of an appendicular system, in the 

 form of scales, leaves, and in the higher plants of sepals, petals, &c. 

 All these organs have a common origin, and this relationship is only 

 partially obliterated throughout life ; so that there is a much closer 

 homology between the organs of one plant, and between the organs of 

 one class of plants, and those of another, than is the case in the animal 

 kingdom. 



In considering what is natural and what is not so, a great deal is of 

 necessity assumed. Naturalists construct for themselves a sort of type 

 or ideal standard of perfection, which does not of necessity exist in 

 nature, but which enables us to gain a clearer insight into the truth. 

 If this be not borne in mind, in speaking of " the laws " of creation, etc. 

 we are likely to be charged with the sin of presumption, and to foster 

 the very prevalent error, that because one hypothesis is shown to be 

 false by arguments derived from another, that the latter is of necessity 

 true. In natural science, that theory has the greatest claims to accept- 

 ance, which satisfactorily explains the largest number of facts, and by 

 means of which our store of knowledge is most augmented. 



For the present purpose, the speaker assumed the correctness of 

 the heretofore generally received opinion of the existence of "species," 

 endowed with a very variable, but a limited power of variation ; and 

 then proceeded to discuss what degree or extent of variability might be 

 considered natural, and what unnatural. The distinction is not 

 always easy, and in many cases it is impossible. Where the variation 

 is slight, and apparently co-existent with a change in the conditions 

 of growth the variation is evidently natural. Allusion was made to 

 such facts as that of peaches and nectarines found growing on the 

 same bough, to alterations effected by changes in climate, &c. When 

 the variation is greater, of course greater difficulty exists in determin- 

 ing whether or no it be natural. Reference was made to the primrose, 

 the cowslip, and the oxlip, which differ in many important points one 

 from the other, but which, nevertheless seem to be variations of one 

 form ; in evidence of which, amongst other facts, are these, that all three 

 have been raised from seeds derived from the same fruit ; and that in 

 the Ilookerian herbarium there exists a specimen wherein a primrose 

 and a cowslip spring from the same stem. Some plants are especially 

 liable to vary ; such are orchids, ferns, grasses, and especially fungi, 

 some of which latter have no less than five different modes of reproducing 

 themselves by as many distinct organs. The speaker was enabled, through 

 the kindness of Professor Buckman, to exhibit specimens illustrating 

 the very curious experiments of that gentleman in ennobling the wild 

 oat, and in producing from the seeds of two so- called species of aquatic 

 grasses, Glyceria aquatica, and Glyceria Jluitans, when grown in a 

 dry soil, a form unlike either of the parent plants, — a form in which 

 the herbage of Glyceria aquatica was combined with 'the inflorescence 

 of Poa trivialis. The experiments of Professor Buckman have the 



