A QUARTER-CENTURY OF PLANT PHYSIOLOGY 5 



ing of printed books there is no end, and each year sees the 

 inauguration of new scientific journals. Physiological literature 

 - — and the literature of science in general — has become such an 

 unwieldy mass that to investigate the records bearing upon 

 any rather Umited subject is now a staggering task in itself. 

 Men have delved into nature, have brought forth the ore of 

 experimental and observational results, have recovered the val- 

 uable metals as interpretations and conclusions, and have stored 

 the latter in the great, hap-hazard store-house of the literature; 

 and now it becomes almost as difficult to find out what is in the 

 store-house and to utilize it as it is to obtain knowledge directly 

 from nature by experimentation. Enormous, confused, hap- 

 hazard, our literature is a veritable muddle, and much of our 

 recorded knowledge will surety be hopelessly lost unless serious 

 attention maj^ soon be directed toward rendering its content 

 practically available. Abstract or reviewing journals and 

 •yearbooks of various kinds are doing their best to help the stu- 

 dent to obtain the references requisite for his work, but they are 

 woefully inadequate, as every physiologist has learned too well. 

 We require a means far more prompt and far more thorough than 

 these, but the future alone can disclose just how such a means 

 may be attained. I have wished here merely to emphasize 

 this feature of recent physiological progress, whereby our science 

 and the sciences related to it seem now tending to smother them- 

 selves b}^ the accumulation of their own products. 



Rise of general -physiology. With the introduction of physical 

 and chemical methods of experimentation and thinking, the 

 two branches of physiology have been merging very rapidly, 

 so that a true physiological science — of animals and plants 

 together — seems already actually to have been formed. This 

 change has occurred almost entirely within the last quarter- 

 century; witness the fact that the first edition of Verworn's 

 Allgemeine Physiologie appeared in 1894, that the first edition 

 of Pfeffer's Pflanzenphysiologie appeared in 1880 and the second 

 (alrnost entirely rewritten), in 1897. These works have done 

 much toward bringing animal and plant phj^siology together 

 and, at the same time, toward introducing chemical and physical 



