1897.] NATURAL SCIENCES OF PHILADELPHIA. 181 



as in the formation of the " hypogynous disk," the growth-waves 

 were too weak. They sometimes, however, reveal to us their un- 

 steadiness. I have frequently found but two carpels in some Phloxes, 

 while once in Phlox Drwnmondii, I found four ! 



With the facts as brought out in the making by nature of Pole- 

 moniaceous flowers, we can see how with a little better regulation 

 of the growth-energy other genera and species of plants might have 

 been created which now have no existence. The wholly suppressed 

 series might have been a five-cleft or a gamosepalous calyx, — the 

 "hypogynous disk," petals or a monopetalous corolla, and the 

 present corolla, might have been another series of five stamens. 

 With these changes other combinations appear. 



We may also see in a study of Polemoniaceous flowers how the 

 varying rhythmic strength influences the whole form of the flower, 

 as well as the development of its individual parts. Dr. Gray says : 

 "the corolla is not always perfectly regular." The tube of the 

 corolla is slightly curved in most species of Phlox. Three longer 

 stamens are always on the upper side of the curve, the two smaller 

 are the lower ones. When the seed vessels of Phlox paniculata are 

 nearly mature, the calyx is two-lipped, the three upper correspond- 

 ing to the upper or outward curve of the tube of the corolla. We 

 may say that it is the irregularity in the growth-waves resulting in 

 organs of varying degress of development, that cause irregular 

 flowers. We have regular flowers when the growth-waves of a 

 plant are all of a uniform intensity. 



PELLUCID DOTS IN SOME SPECIES OF HYPERICUM. 



Many species of Hypericum present small black dots on the stems, 

 leaves or other portions of the plant. In H. corymbosum Muhl., 

 the stem and lower leaves have these dots profusely scattered over 

 the surface, those on the stem being generally somewhat elongated, 

 after the manner of suber cells as usually seen in the young bark or 

 epidermis of woody plants. Examining the series of leaves in suc- 

 cession up the stem, we find the uppermost leaves nearly destitute of 

 black dots, a few being found chiefly near the margin. Starting 

 again from below upward, we find that as we advance the pellucid 

 dots, wholly absent in the lowermost leaves, begin to be compara- 

 tively scarce near the midrib. As they come into existence, the 

 black dots disappear. The pellucid dots increase in numbers with 

 each series of leaves — the black dots seem to give up the ground to 

 the pellucid ones — till, when the much reduced leaves beneath the 

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