March 25, 1909] 



NATURE 



93 



pale, bulky, with abundance of undigested fat, and 

 showed evidence of putrefactive changes. In the fseces 

 and stools obtained by calomel catharsis from the upper 

 intestint', the normal bacilli, viz. gram-negative forms 

 belonging to the B. coli commiDiis and B. lactis 

 aerogenes group, appeared absent, while the bacterial 

 elements belonged to the gram positive group, the 

 most constant being one which the author named 

 B. infantilis. 



As improvement set in there was a gradual return 

 to normal bacterial conditions. The author says that 

 the relation of B. infantilis to the genesis of infantil- 

 ism must be left open, but it is certain that in its most 

 extreme form intestinal infantilism is associated with 

 the persistence and dominance of types of intestinal 

 flora which belong to the period of infancy, and the 

 persistence of which, in the third to eighth year of 

 life, must be regarded as pathological. 



The author believes that the cause of arrested de- 

 velopment is due to serious defect in the power of 

 absorption and digestion of food-stuffs. In treating 

 these cases he found that drugs, purgatives, and in- 

 testinal antiseptics, gave little help. \\"ith careful 

 hygienic and dietetic supervision the intestinal dis- 

 turbance was checked, and gradually, although often 

 with the utmost difficulty, an increase of weight 

 followed. 



The observations on which this study is based were 

 of a purely clinical nature, and the deductions cannot 

 be accepted as conclusive, but they are suggestive 

 and interesting, and are presented by an investigator 

 of experience. L. G. A. 



PLASTICITY IN PLANTS. 

 The Heredity of .Acquired Characters in Pla)tts. By 

 the Rev. Prof. George Henslow. (London : John 

 Murray, 1908.) Pp. xii+107; 24 illustrations. 

 Price bs. net. 



THE object of Prof. Henslow's book is " to prove 

 that evolution — so far as plants are concerned — 

 depends upon the inheritance of acquired characters." 

 "This was Darwin's contention." See, for instance, 

 the summary statement on p. 424 of the sixth edition 

 of the " Origin of Species " ! " Present-dav ecologists 

 who study plants in nature are all at one in accept- 

 ing the fact that evolution in plants is the result, 

 not only of a natural response to the direct action 

 of changed conditions of life, by means of which thev 

 evolve new structures in adaptation to their new 

 environments, but that these acquired characters can 

 become hereditary." The author calls this, for some 

 strange reason, " the true Darwinism." His general 

 argument, which is backed up by many very 

 interesting facts, may be illustrated by taking the 

 following instance : — " .\ certain plant of a 

 Trichosanthes, happening to have its tendrils touch- 

 ing the wall of the glass frame in w-hich it grew, 

 instantly developed a number of minute pads which 

 adhered to the wall, though such a structure is not 

 known to exist in the cucumber family at all." A 

 common sea-weed, Plocamitini coccineum, makes 

 similar pads if a tip happen to press against another 

 sea-weed. Mere mechanical force produces through 

 NO. 2056, VOL. 80] 



response hereditary structures. In the American 

 \"irginia creeper the tendrils form adhesive tips when 

 thev touch the wall. These are not hereditary, but 

 the power to form them is. In the Japanese Virginia 

 creeper they are partially developed before there is 

 any contact with the wall. " They are hereditary, 

 but quite useless until contact has taken place, when 

 thev at once begin to develop into perfectly adaptive 

 structures. Such is obviously a result of a response 

 with adaptation to a purely mechanical contact of 

 the soma with the wall, and before any reproductive 

 germ-cells exist." As the author says, "botanists 

 have this great advantage ; they have facts to deal 

 with, and no theories whatever to maintain." 



Prof. Henslow's book is of much value in giving 

 fine examples of the plasticity of plants under external 

 stimulus, i.e. of the appearance of new features in 

 unwonted conditions. But it is difficult to decide how 

 far the observed change of structure in an individual 

 plant is a direct result of the environmental influence, 

 and how far it is due to the liberation or inhibition 

 of constitutional possibilities established long ago. 

 The author thinks the first view is the correct one, 

 and he points out that similar modifications are 

 exhibited in similar conditions by many quite 

 unrelated plants. As to the heritability of modifica- 

 tions the individual occurrence of which is recognised 

 by all, Prof. Henslow admits that changed plants may 

 at once begin to change back again when the novel 

 stimulus is withdrawn, but he maintains that the 

 acquisition may last long enough to show that it 

 was hereditary. This is a crucial point, and should 

 have been worked out more precisely. The author 

 gives cases like the following : — Lesage made plants, 

 such as garden-cress, succulent, by watering them 

 with salt water ; plants raised from seed of the some- , 

 what succulent salted plants were still more succulent 

 in the following year. 



The general conclusion of Prof. Henslow's book 

 is that " the origin of species is due to the joint 

 action alone of the two great factors of evolution — 

 Variability and Environment — without the aid of 

 natural selection ; although we are, and are likely 

 to remain, profoundly ignorant of the mysterious 

 process (of Response) within the organism by which 

 it is effected." 



AGRICULTUR.il CHEMISTRY. 

 Elementary Agricultural Chemistry : a Handbook for 

 Junior .-Igricultural Students and Farmers. By 

 Herbert In-gle. Pp. ix + 250. (London: C. Griffin 

 and Co., Ltd., 1908.) Price 4^. 6d. net. 



TE/\CHERS at agricultural schools and colleges 

 are placed in the difficult position of having to 

 teach a branch of applied chemistry to pupils who 

 have little time, and often less inclination, to study 

 pure chemistry. The best method of procedure has 

 probably not so far been found, nor has agricultural 

 chemistry as yet fallen into the hands of the text-book 

 writer to anything like so complete an extent as 

 its parents on both sides. It is, however, pretty clear 

 what the agricultural student ought to be able to 

 do. He should have a good working conception ot 



