182 PROCEEDINGS OF THE ACADEMY OF [1897. 



flower are reached, scarcely any but the pellucid dots are found. 

 They reappear again in numbers on the petals. 



It is singular that though there is an evident correspondence in 

 the increase of pellucid dots and the decrease of the black dots, no 

 genetic relationship can be discovered. In no instance was there 

 any evidence of a transmutation of a black dot to a pellucid one. 



The dotted structure of other species growing on my ground was 

 therefore examined. These were Hypericum perforatum, H. Buck- 

 leyi, H. Kahnianum of our country, and H. Androscemum, H. caly" 

 cinum and H. Moserianum of the old world. H. perforatum fur- 

 nished the most interesting subject for comparison. The lower 

 leaves, given up wholly to black dots in H. corymbosum, had only 

 pellucid dots, and in none of these were black dots numerous. In- 

 deed, it was only in the uppermost leaves that a few black dots were 

 found, and these sparingly distributed near the outer edges. On 

 the petals also the black dots are sparingly found. 



It is apparent from what has been stated in regard to H. corym- 

 bosum that the energy productive of the black dots is different in 

 degree from that productive of pellucid dots. We may further con- 

 clude that these varying degrees of growth-energy had but little 

 to do with the differentiation of these two species. One species 

 could readily be transformed to the other as each degree of energy 

 was in control. 



In H. Kalmianum and H. Buckleyi pellucid dots are profuse. No 

 trace of black dots could be found. From what has been already 

 noted, they are not to be expected where the pellucid dots abound. 



In the European H. Androscemum the whole surface is minutely 

 pellucid-punctate. The mid-rib and veins are also pellucid. At 

 various points along the lines of these veins are, however, small 

 swellings, more or less orbicular, as if they had been originally 

 pellucid dots, and that lines had been thrown out to connect the 

 dots with each other. In H. calycinum there are similar connec- 

 tions, and besides a few scattered pellucid dots ; but these are not 

 round but pyriform, one end tapering into a narrow tail. If a little 

 more prolonged, we should have just such connections as we find in 

 H. Androscemum. In H. Moserianum, we find the surface profusely 

 covered with dots, not very pellucid, apparent though they are when 

 held up to a bright light. Some of these are wholly individualized 

 and isolated, but others have sent out a line as yet unconnected, but 

 the great majority have had the lines connected, and have formed a 



