146 



NA TURE 



[December 19, 1907 



further than the expression of certain facts of general 

 observation, which in themselves constitute no proof. 

 Schwendener's theory of the influence of mechanical 

 contact has long- held the field, in spite of the fact 

 that no such contact can be invariably proved to exist, 

 or even to exert any mechanical action ; so much so! 

 in fact, that it has been regarded as possible to dilute 

 the theory to one of vague "stimulation." Dr. 

 Iterson, by following along the well-worn paths of 

 previous observers, has reached very similar conclu- 

 sions; and it must be admitted that continual study 

 of the best exhibitions of the uniform construction of 

 vegetative shoot-systems naturally impels the observer 

 to the old and familiar view of Hofmeister, that 

 appendages cannot help themselves, but arise in the 

 next " widest gap " between pre-existing ones, as 

 they are seen to do; such a statement represents no 

 solution of the problem, but is, in fact, a confession of 

 failure. 



On the other hand, by approaching the subject from 

 the standpoint of floral ontogeny, in which the most 

 complex phyllotaxis-systems can be observed develop- 

 mg before one's eyes according to a perfectlv defined 

 architectural plan, in which the relation of 'the indi- 

 vidual members may, however, be practicallv anything 

 whatever, wide gaps being left in some places, spirals 

 mixed with circular construction, and members 

 apparently "omitted," as well as appearing "out of 

 their turn," an investigator equallv inclines with 

 Schumann to the view that contact-relations present 

 no contributory cause whatever to the phenomena of 

 the initial phases, which can onlv be referred to 

 autonomous growth-impulses within the substance ol 

 the shoot-apex; a region which, consisting as it does 

 of undifferentiated cell-units, is beyond further possi- 

 bility of observation. Among the general conclusions 

 lor straightforward " constant-phvllotaxis, " Iterson 

 reiterates the stock considerations of " bulk-ratio " 

 "contact-relations," and the principle of the "widest 

 gap" (p. 291). 



The fallacy of the widest gap has been exposed over 

 and over again ; it is sufiicientiv obvious to the un- 

 prejudiced eye in the appearances presented at the 

 apex of the common Fern, or shoots of Water-lilies- 

 pnmordia do not invariably arise In close contact with 

 each other, but may be widely spaced out at first. 

 ihe same want of contact, or any connecting sequence 

 between one series of members and the next, is a 

 common phenomenon in floral ontogeny which also 

 includes cases of such absolute irregularity that the 

 necessity for a " mechanical law " for their produc- 

 tion becomes an absurdity ; while in examples of per- 

 fect regularity of construction, the case of extreme 

 mathematical interest centres in those few instances 

 in which successive whoris do not fall into the gaps 

 of their predecessors at all, but are accurately super- 

 posed; such cases occur in certain living species of 

 .Mcsembryanthemum, though the significance of this 

 formation in the case of fossil plants may still be open 

 to question. It is thus a matter for regret that Iter- 

 son should revive the conceptions of " close-contact " 

 and " widest-gaps," which have seen so much ser- 

 vice in the past; while again the conception of " bulk- 

 ratio," or the relative size of the primordium with 

 NO. 1990, VOL. ']']'] 



regard to the axis on which it is " inserted," though 

 extremely useful in dealing with the difliculty of dis- 

 tinguishing between systems which involve numerals 

 of the same summation series, e.g. 3:5:8, &c., 

 can yield no practical solution of the difference, for 

 example, between a 3 : 5 construction and a 3:4, 

 or, again, of the essential difference between spiral 

 and circular arrangement. It is also sufficiently 

 obvious that the causes which determine the relative 

 rates of growth (which lie behind the relative size) 

 must have existed in the actual substance of the 

 growing-point some time before the primordia be- 

 came visible to the eye as a definite outgrowth, and, 

 admitting the absence of any necessity for close-con- 

 tact, the spacing of the new centres of growth is pre- 

 sumably more important than their actual size; once 

 the centres are initiated, the new growth-impulses 

 from them are continued until they ultimately make 

 lateral contacts as a wholly secondarv phenomenon. 



Dr. Iterson's volume affords an admirable intro- 

 duction to the subject, and most of the branches are 

 indicated; considerable value attaches to the risum& 

 of the theories of Schwendener and Celakovsky, copi- 

 ously illustrated with excellent figures (more than 100 

 text-illustrations, and 16 plates); these bear sufficient 

 witness to the enthusiasm of the author in this most 

 absorbing field of speculation, though when all is 

 said we appear to be no nearer the solution of the 

 problem than ever ; it only gains *n complexity where 

 it seems to be most regular and simple; since an 

 absolutely irregular construction can clearly have no 

 explanation at all, it simply grows as one sees it 

 grow, and can neither be accurately described nor 

 imitated. To those who seek for the inner and ultim- 

 ate cause of the phenomena, the subject still presents 

 an indefinite field of research. 



Few botanists appear to realise the extent to which 

 a proper appreciation of the subject of phyllotaxis is 

 involved in the morphological consideration of plant- 

 growth, and floral construction and even phylogeny ; 

 the marvellous standpoint that a dimerous flower is 

 simpler, and therefore more primitive, than a trimer- 

 ous one, and a trimerous than a pentamerous, con- 

 stitutes one of the vitiating factors of the systematic 

 work of Eichler, and is still reflected in the modern 

 German school of classification. 



ORG.iNIC CHEMISTRY FOR MEDICAL 

 STUDENTS. 

 Te.\t-book of Organic Chemistry for Medical Studoits. 

 By Dr. G. v. Bunge. Translated with additions by 

 Dr. R. H. A. Plimmer. Pp. ix + 260. (London : Long- 

 mans, Green and Co., 1907.) Price 6s. net. 

 THE rapid advance which has marked the pro- 

 gress of physiological chemistry in the last 

 twenty years, owing mainly to the remarkable re- 

 searches of Prof. Emil Fischer, has emphasised the 

 necessity of a sound knowledge of organic chemistry 

 for all students of medicine. But organic chemistry 

 has undergone developments in many other directions, 

 and new compounds have multiplied at a most be- 

 wildering rate. It is clearly undesirable for the 

 student of medicine to become acquainted with any 



