412 BOTANICAL BIOLOGY. 



sliown to serve as food for ants ? So far from this explanation beinj; 

 far- fete lied, Belt found that the former "tree is actually unable to exist 

 without its guard," which it could not secure without some attraction 

 in the shape of food. One fact which strongly impresses me with a be- 

 lief in the adaptiv'e significance of vegetative characters is the fact 

 that in almost identical forms they are constantly adopted by plants of 

 widely different aflinity. If such forms were without significance one 

 would expect them to be infinitely varied. If however they are really 

 adaptive, it is intelligible that different plants should independently 

 avail themselves of identical appliances and expedients. 



Although this country is splendidly equipped with appliances for the 

 study of systematic botany, our universities and colleges fall far be- 

 hind a standard which would be considered even tolerable on the Con- 

 tinent, in the means of studying morphological and physiological botany, 

 or of making researches in these subjects. There is not at the moment 

 anywhere in London an adequate botanical laboratory, and though at 

 most of the univ^ersities, matters are not quite so bad, still I am not 

 aware of any one where it is possible to do more than give the rou- 

 tine instruction, or to allow the students, when they have passed 

 through this, to work for themselves. It is not easy to see why this 

 should be, because on the animal side the accommodation and appli- 

 ances for teaching comparative anatomy and physiology are always 

 adequate and often palatial. Still less exj)licable to me is the tend- 

 ency on the part of those who have charge of medical education to 

 eliminate botanical study from the medical curriculum, since histori- 

 cally the animal histologists owe everything to botanists. In the sev- 

 enteenth century, as I have already mentioned, Eooke first brought 

 the microscope to the investigation of organic structure, and the tissue 

 he examined was cork. Somewhat later. Grew, in his "Anatomy of 

 Plants," gave the first germ of the cell-theory. During the eighteenth 

 century the anatomists were not merely on a hopelessly wrong tack 

 themselves, but they were bent on dragging botanists into it also. It 

 was not until 1837, a little more than fifty years ago, that Heule saw 

 that the structure of epithelium was practically the same as that of the 

 parenchyma i^laniarum vih\c\i Grew had described one hundred and fifty 

 years before. Two years later Schwann published his immortal theory, 

 which comi)rised the ultimate facts of plants and animal anatomy 

 under one view. But it was to a botanist, Von Mohl, that in 1846, the 

 biological world owed the first clear description of protoplasm, and to 

 another botanist, Cohn (1851), the identification of this with the sar- 

 code of zoologists. 



Now^ the liistoric order in discovery is not without its significance. 

 The path which the first investigators found most accessible is doubt- 

 less that which beginners will also find easiest to tread. I do not my- 

 self believe that any better access can be obtained to the structure 

 and functions of living tissues than by the study of plants. However, 



