LITERARY NOTICES. 



849 



were constant in any one part of a plant, in 

 the course of time the respose would become 

 hereditary. Thus the adhesive pads of cer- 

 tain creepers (Ampelopsis) form before the 

 tendril has come in contact with the wall. 

 A similar development is true of the aerial 

 roots of ivy, etc. 



Nectaries have developed according to the 

 same theory — namely, insects having been at- 

 tracted to the juicy parts, withdraw the liquid 

 and cause a flow of secretion, and finally a 

 gland results. This is not unlike the state- 

 ment that the excellence of milch-cows is 

 largely due to the stimulation produced upon 

 the milk-glands by the hands of the milker. 

 Floral nectaries are correlated with pollina- 

 tion, they being invariably so placed as to 

 subserve cross-pollination by insects. 



It is shown by a long list of examples 

 that sensitiveness and irritability are com- 

 mon phenomena in plants, whether in proto- 

 plasm, movements of organs, or formation 

 of tissues, and the theory in hand is but an 

 application of a general principle to the de- 

 velopment of a particular part of the flower. 

 The existing floral structures have been 

 evolved under the mechanical and physio- 

 logical impulses due to insect agencies. 

 The colors of flowers, with all the display of 

 streaks, etc., as path-finders to the nectaries, 

 accord with the theory. " Instead, there- 

 fore, of a flower having first painted a petal 

 with a golden streak to invite the insect and 

 to show it the right way of entering, the first 

 insect visitors themselves induced the flower 

 to do it, and so benefited the future comers." 

 The author's discussion of heterostylism — 

 i. e., the different lengths of styles and sta- 

 mens in the same species — is of great inter- 

 est, especially that portion which deals with 

 the origin of this condition in flowers. He 

 assumes a homomorphic form as the primi- 

 tive type, and dimorphism has been effected 

 by varyiag degrees of stimulus, through in- 

 sects, being applied to stamens and pistils, so 

 that one set of organs may have been raised 

 while the other was lowered. The lengths 

 finally became so fixed that the best adapta- 

 tion for cross-fertilization is thereby secured. 

 This view not only ascribes to insects the 

 original cause of variation, but that of the 

 final stability in the dimorphic or trimorphic 

 type. In summing up the treatment of meta- 

 morphosis of flowers, both progressive and 



VOL. XXXIII. — 54 



retrogressive, Prof. Henslow concludes that 

 the vascular cord is the fundamental floral 

 unit, and, as these cords are identical before 

 differentiation, it is not beyond expectation 

 that petals may arise in place of stamens or 

 stamens take the ordinary position of pistils. 

 The primary cause may be less apparent, but 

 doubtless it is in accordance with the govern- 

 ing action of environment modified by hered- 

 ity. The conclusion drawn upon the some- 

 what obscure subject of fertilization is, " not 

 that self-fertilization is per se in any way in- 

 jurious, but that flowers which are normally 

 sterile by having become so highly differen- 

 tiated through insect stimulation do not now 

 spontaneously set seed, and self-fertihzation 

 is not so efficient as crossing." Prof. Hens- 

 low has endeavored to make " a good theory 

 of variation," and gives a direct cause for 

 structural forms. He claims that the use of 

 the expression " natural selection " leaves 

 the subject where it was before. " Instead, 

 therefore, of using this term as the cause of 

 anything and everything, I prefer to attribute 

 effects to hypertrophy, atrophy, resistance to 

 strains, responsive action to irritations, and 

 so on." It is possible that "natural selec- 

 tion " may underlie all these, and be so under- 

 stood by many. As to the origin of a flower, 

 the author thinks that it is only necessary to 

 assume a leaf-bud, some of the members of 

 which have differentiated into floral organs 

 of the simplest type, as seen in the gymno- 

 sperm. Insects frequently search for pollen 

 only, and by piercing the juicy tissues of 

 such primitive flowers would introduce a 

 series of changes which in time result in 

 conspicuous blossoms. Whether or not the 

 theory is accepted in all its many bearings, 

 it is certain that every botanist must feel 

 under obhgations to Prof. Henslow for the 

 excellent volume he has prepared, for the 

 great array of facts therein, and the clear, 

 concise manner in which the theory has been 

 presented from first to last. 



Industrial Liberty. By John M. Bonham. 

 New York : G. P. Putnam's Sons. Pp. 

 414. Price, $1.75. 



The author of this essay has evidently 

 thought long and well on his topic. He has 

 sought to treat the subject of industrial lib- 

 erty in a manner somewhat different from 

 that in which it has usually, been discussed; 

 and, aiming to keep in view principles rather 



