Boo 



NATURE 



[DLuL:.;i.LK I, 192, 



PaAI repeated and confirmed Boysen- Jensen's result* 

 and added the important observation that the stimulus 

 can pass a slice of pith o*i mm. thick impregnated 

 with gelatin intercalated Ixjtween the receptive and 

 responsive regions. Similar work has l>een since 

 carried out by Stiirk on thigmotropic and traumato- 

 tropic stimuli. This experimenter brought to light 

 the fact that the receptive tip of one plant may be 

 transferred to the base of another and after stimulation 

 may determine curvature in the latter. Furthermore, 

 the certainty of this resptmse to thigmotropic stimuli 

 depends, other things l)cing equal, upon the phylo- 

 genetic affinity of the two parts. Recently Snow has 

 shown that the gravitational stimulus is transmitted 

 across protoplasmic discontinuities in the seedlings of 

 Viciajaha. 



From the foregoing it is quite evident that proto- 

 plasmic continuity is not requisite for the transmission 

 of stimuli in the higher plants. The localisation of 

 the positive and negative responses respectively to 

 one side of the reacting region and the velocity of 

 transmission will not allow us to assign the propagation 

 to simple diffusion ; but these characteristics j>oint 

 clearly to the transpiration-stream. It affords the 

 localised delivery and the necessary velocity. Intro- 

 duction of the requisite hormones may be effected 



through uninjured cells, or along moist wound surf- r- 

 This consideration explains how it is that conti: 

 between the vascular bundles of the receptive tip ! 

 those of the responsive base is not necessary to s. 

 the reaction. Thus, there is great prob 

 these plants, as in Mimosa, the transmit 

 is effected by the transport in the transpiruii 

 of a substance derived from the receptive ■ 

 conveyed by this means in the wood of the va- 

 bundles to the responsive region. We may im 

 that this substance is first liberated into the tran 

 tion stream by changes in the permeability 01 ;., 

 receptive cells, and response is evoked in the reactiv< 

 cells by similar alterations in permeability. 



Whatever the intimate mechanism of Uie system is 

 the subject of the transmission of stimuli thr' 

 plant tissues offers a striking example of the swi: 

 the pendulum of scientific opinion. The view ' 

 upon superficial resemblances, that the va 

 bundles are the nerves of plants*, was long a! 

 but now we see there is clear evidence t 

 actually transmit stimuli from the sensory to the i 

 regions, and so perform the function of nerves, 

 foregoing summary of recent work indicates ho\' 

 differently in detail this ronnexion ''= *-^» .Ki.M.r-i j-, 

 plants and animals. 



Obituary. 



Mrs. Hertha Ayrton. 



APPEAL is made to me to give some account of 

 Hertha Ayrton, the wife of my former colleague, 

 who died last August. 



" Is the study of heredity a science or a pure 

 romance ? " asks Mrs. Trevelyan, in her biography of 

 her mother, Mrs. Humphry Ward. I would set the 

 question in another form : Is das ewig Weibliche to be 

 suppressed by science ? Mrs. Ayrton was one of those 

 who aspired to prove that woman can be as man as 

 an original scientific inquirer. Did she succeed ? If 

 we are to frame a psychology of the scientific mind, 

 regarding this as a species apart, we must carefully 

 note and analyse the doings of such as she. I have 

 but small qualification for the office, yet as she was 

 my colleague's wife and we often met and were in fair 

 sympathy, I was able to take notice of her idiosyn- 

 crasies and of the conditions under which she was 

 placed. 



Ayrton and I met originally in the autumn of 1879, 

 when we were appointed the first two professors of 

 the City and Guilds Institute and set the ball of 

 technical education rolling in London ; the ball rolled 

 well and proved to be fissiparous but no one of the 

 small band who gave it shape in the City and West 

 End ever received the slightest recognition from the 

 Guilds, their masters — and most of these have com- 

 mitted hari-kari as concerted workers in education. A 

 strange world is ours and if we worked otherwise than 

 for the sake of working, we should do little. 



AjTton had a peculiar experience : his then (first) 

 wife — his cousin, Mathilda Chaplin — was a woman who 

 had acquired merit in the cause of women's rights, as 

 she was one of the three, I believe, over whom the 

 fight first raged in Edinburgh whether women should 



NO. 2822, VOL. 112] 



be admitted to the study of medicine. When I met 

 her, her health was more than failing. She was an 

 ethereal being, a woman of infinite charm of m 

 but above the world — a mature Melisande ; in„., 

 when I first heard Debussy's opera her memory w;: 

 recalled to me by the peculiar rhythm and tone (.i 

 its melody. Her daughter, Mrs. Zang>\ill, has inherited 

 not a few of her mother's characteristics — espc ' " 

 her charm of voice. Her chief occupation was i 

 reading, from penny-dreadfuls upwards, in which si 

 ran a caucus race with our erratic friend, John Perr;. 



Ayrton married his second wife in 1885. If I were 

 to compose an opera with my scientific friends as the 

 characters, I should associate the Melisande then": 

 with the first Mrs. A)Tton ; I should not quite kno\^ 

 where to place the second musically but it would be 

 near to Brunhilde, as she had much of the vigour of 

 Wotan's masterful daughter and, at least, aspired to 

 be an active companion of scientific heroes — a race 

 far above Wagner's dull and degenerate Teutonic god> 

 be it said. 



Sarah Marks was the daughter of intelligent but poor 

 Jewish parents in Portsmouth. She was a * " 

 child and was early sent to a school in London 

 by her paternal aunt, who became Mrs. Hartog ; M; 

 Hartog was a teacher of French in London. Mr.^ 

 Hartog was the mother of Numa Hartog, Philip Hartog 

 and the professor of botany in Cork ; also of two 

 daughters, one very clever, a talented painter, who 

 married Dr. Darmstadter of Paris ; the other earned 

 her living as a musician. Numa Hartog died early, 

 after a most brilliant university career and seems t" 

 have been unusually clever. Mrs. Marks had fou: 

 undistinguished children, besides Sarah ; nothing 15 

 knoNNTi of her parents. Mrs. AjTton's ability, however. 



