PHYSIOLOGICAL 301 



years ago by Dr. F. H. A. Marshall, Reader in Agricultural Phy- 

 siology at Cambridge, and it has been repeatedly successful since. 

 But Voronoff was able to effect the transference of chimpanzee or 

 of baboon testes into man, and apparently with very good results 

 — as regards memory as well as muscles, as regards will-power as 

 well as blood-pressure. 



But most of Voronoff's successes (we know too little of the 

 failures) have been between animals of the same species. Thus a 

 decrepit ram, grafted at twelve years, renewed its youth in three 

 months and was vigorous till it was twenty. Dr. Marshall vouches 

 for the reinvigoration of an enfeebled Algerian bull, which was in 

 good fettle four years after the graft. In the case of immature male 

 sheep, whose reproductive hormones have not begun to tell, 

 Voronoff claims that a testicular graft hastens growth and increases 

 general vigour, affecting, for instance, the quality and length of the 

 wool. But there are many possible snags in these investigations, 

 and while the Austrian experimenter's work is of great interest, 

 there is need for scientific caution. Let us hasten slowly. 



ILLUSTRATIONS OF PLANT PHYSIOLOGY 



In uniting Plants and Animals under the common title Organisala 

 (1735), Linnaeus was far ahead of his time, for it was not till about 

 a century later that the fundamental unity of plant and animal 

 life was generally recognised. That recognition was won by Claude 

 Bernard's famous book, Phenomhies de la Vie communs aux Animaux 

 et aux Vegetaux (1879). The differences between plants and animals 

 are great ; but the resemblances are greater. 



In our sketch of animal physiology we began with contractility 

 and irritability — the power of movement and the power of feeling — 

 and then proceeded to show how these "master-activities", as Sir 

 Michael Foster called them, are kept agoing by the ancillary or 

 sustentative functions of nutrition, respiration, excretion, and so 

 forth. But while plants have their interesting movements and 

 reactions to stimulus, their main activity is groivth. The matter and 

 energy of their income is mainly expended in adding to their size, 

 which is in many cases slow of i caching a limit. Even when an 

 individual plant remains small, there may be a lavish expenditure 

 in discontinuous growth, which spells asexual multiplication. 

 Though no doubt extreme, the Big Trees or Sequoias of California 

 are but characteristic, with an enormous intake of matter and 

 energy, sometimes prolonged well over three thousand years; and 

 this is mainly expended in the attainment of a huge body which 

 has to be lifted and held against gravity and wind, even to a height 

 of 300 feet in the aii*. Whereas animals change most of the chemical 



