202 Macfarlanc — Cwrent Problems 



with the possibilities of protoplasmic fusions and transfusions, 

 as well as nutritive adaptability. 



No fact impressed me more in the study of Cytisns Adami 

 as a probable graft hybrid, than the remarkable differences in 

 the epidermal nuclei of the composite organism. While those 

 of the arborescent C. Laburnum portion are relatively small 

 and rich in chromatin material, those of the smaller parent 

 portion, C. purpureus and of the hybrid, are large and much 

 less refractive in their nuclei. 



At the present day the complaint is sometimes made that 

 plant taxonomy is being neglected for the cultivation of plant 

 morphology and physiology. In one sense the complaint is a 

 just one. But is it not true that we are only beginning to 

 realize what plant individuals, plant varieties and plant species 

 are, as we compare cell with cell, and tissue mass with tissue 

 mass ? That this is correct is evidenced by the rapidly grow- 

 ing popularity of that most recent departure which I will now 

 shortly touch on, namely : 



(e) Ecological Cytology. — That cells, and therefore plant 

 parts, can be molded by their surroundings, we accept as 

 proved by experiment. Shortly, it may be said that environ- 

 mental stimuli act on every living plant cell, while the cell 

 reacts temporarily or permanently to the stimulus. This fun- 

 damental law of plant life is only beginning to be realized in 

 all its fullness. But while the general relationship of plants 

 to their surroundings in respect of form, consistence, size and 

 color should be noted, it soon becomes evident that these data 

 have to be corrected and supplemented by a study of indi- 

 vidual cells. It is a significant omen of present day progress 

 that Schimper's splendid work on plant distribution recognizes 

 continually not merely those agents which we class as the 

 environmental stimulants, but equally the cytological changes 

 which such stimulants produce. So exact is this line of 

 inquiry becoming that we may soon be able to speak not only 



