1895.] Development of Vegetable Physiology. 395 
development, including the reciprocal influence of proximity. 
Of the names prominent in this connection, those of Coville, 
Trelease and Macmillan are especially worthy of mention. 
The last has done good service by calling attention to the 
significance of tension lines, in his account of the ‘‘Meta- 
spermze of the Minnesota Valley.” There is a phase of phylo- 
genetic study which has received some attention of late, in 
form of the breeding of plants. It is a subject especially 
adapted to experiment station work. The leader in this line 
of research, L. H. Bailey, has also materially promoted eco- 
logical studies by his numerous biogenetic and other writings. 
Coming to physiology, sensu stricto, we find the domain of 
the science so well defined and its several areas so well culti- 
vated that aclear statement of its main problems is now pos- 
sible. Not much advancement was made before the begin- 
ning of the present century. The most notable achievements 
had been the publication of Hales’s brilliant work on the pres- 
sure and movement of sap, which introduced the physical 
side of physiology to the world, and Ingenhousz’s equally en- 
tertaining volume upon his discoveries regarding the uses of 
green organs, which introduced the chemical side of physiol- 
ogy to the world. The century was ushered in by Knight's 
classical essays, in which it was first pointed out, among other 
things, that there was a substantial reason why roots grow 
downward and stems upward, and by De Saussure’s researches 
upon respiration and other chemico-physiological matters. It 
is worth mention that Hales, Ingenhousz, Knight and De 
Saussure were not botanists, although they cultivated botan- 
ical subjects; neither were Senebier, Du Hamel, Dutrochet, 
Liebig, Boussingault and others, who assisted in laying the 
foundations of the science, but were physicists, chemists and 
horticulturists. And to thisday many important data are con- 
tributed to the science by workers in other fields. 
Thus facts accumulated, important discoveries were made, 
and the mysteries of the life processes in plants were gradu- 
ally unfolded. But it was not until 1865 that the science was 
' given the commanding position due to it. Then appeared 
the first treatise which set forth the phenomena and laws of 
vital processes with due regard to proportion, and with clear 
Philosophical insight. Sachs, in his ‘‘Experimental Physiol- 
ogy,” became the founder of the science in its modern aspect. 
He set forth with critical discrimination the most important 
