Retrospective Criticism, ^79 



felling a sycamore tree, and of an unusual production of clustered buds on the 

 crown or collet of a dahlia tuber. Now, there are so many instances of the 

 incredible number of gems or buds developable from the radical plate of a 

 bulb, the crown of a herbaceous perennial, or from the collet or indeed any 

 part of the stems of such trees as the myrtle, hawthorn, elm, &c., that it is 

 rather a proof of the validity of the idea that what are called normal buds are 

 illimitable, or indeed infinite as to numbers. If we consider the structure of 

 a single shoot of any dicotyledonous tree, we must admit the practicability of 

 making this divide itself into a hundred others, thereby gaining a clear idea of 

 the accidental cause of the birdnest-like tufts of spray seen on birch and 

 other trees ; for, if the leading or topmost bud of a shoot be destroyed in the 

 first stage of its growth, its lengthening tendency is stopped, and all the buds 

 which would have been exhibited along the whole length of the perfected 

 shoot will be found crowded together round the base ; whence, if the tree be 

 vigorous, they will in time be developed, and hence a group of many shoots 

 will be produced. But, whether singly, or in great numbers, they must ne- 

 cessarily have the same origin. 



Dr. A. T. Thomson's notion of the miscalled medullary rays being the 

 tracks of buds is untenable ; because these rays exist where no buds ever 

 appear, as on the internodes of the grape vine, for instance : and, besides, 

 these rays are convergent to, not divergent from, the pith ; and are in fact 

 perpendicular partitions, extending from the bottom to the top of the trunk ; 

 and with which were the buds connected, the latter would appear in perpen- 

 dicular ranks one above another, and not dispersed irregularly as they usually 

 are. The doctor's idea that the number of normal buds is definite is certainly 

 erroneous, especially if we only consider what numbers are crowded together 

 in the single eye of a potato. Few persons, perhaps, have proved this, as it was 

 once my duty to do ; "and thereby hangs a tale." I once served a gentleman 

 who was a native of Manchester, and who very much regarded every thing 

 originated in that neighbourhood. Of course we had all the crown bobs, the 

 top-sawyers, and roaring lions from that district ; among other things were 

 received two large specimens of a famous new and scarce potato then in great 

 estimation about iVlanchester. I had the charge of these precious morsels, 

 with strict orders to make the most of them. Accordingly, it occurred to 

 me to propagate the potatoes exactly as dahlias are now done. I nearly 

 buried them whole in the floor of a peach-house then in work ; and as the 

 shoots sprung up 4 or 5 incbes high, they were slipped off and planted in rows 

 in the open air on a piece of well-prepared ground. The slip[)ing and planting 

 began in April and was continued till the beginning of July ; and even then 

 the tubers continued to produce shoots. I took no note of the number of 

 slips obtained from each eye, nor of the numbers collectively from both tubers, 

 but they were considerable,; and I well remember liaving five or six rows 

 across a quarter of the garden, which yielded a large increase of tubers, 

 though much smaller generally than if they had been, as they were for several 

 years afterwards, raised-from sets in the common way. I mention this, as a 

 practical proof of how very complicated a member the single eye of a potato 

 is ; and as dahlias are of similar chai-acter, it is not to be wondered at, that 

 a tuber, perhaps of a peculiar conformation, should be studded with a swarm 

 of buds abnormally exhibited. 



The main question is, whether there can possibly be such a thing as an 

 adventitious bud, that is, one which had no previous existence in the system. 

 I humbly presume there cannot, and, if not one, how can thousands be ex- 

 hibited ? It maj be conjectured that, when buds appear in excessive num- 

 bers, they must be new creations; but of what and whence are they created? 

 That the vital membrane produces both buds and roots simultaneously is 

 undeniable: but these are not fortuitous; they are pre-existent parts or 

 extensions of that membrane whence all growth proceeds. The only instances 

 we have of what may be called new creations, are the sports or variations 

 which occur among highly cultivated seedlings, owing to the intermixture of 



