1886.] NATURAL SCIENCES OP PHILADELPHIA. 345 



Acer rubriim, Phytolacca decandra, 3Iuhlenbergia diffusa, Poten- 

 tilla canadensis, the last two to some extent in the wood. 



All the kinds, however, o;rew in the vicinity of the acre of 

 woodland, though not within its limits, and it was eas}' to note 

 that they had grown from seeds falling or brought to the black- 

 berry patch during the last three or four years. Those who are 

 familiar with the seeds of these plants will understand that there 

 is nothing special about the seeds of these species that would 

 easily lead to their being brought there by birds that might 

 rendezvous in the thickets. We must look to the wind as the 

 chief agent in transporting them there. This being the case, we 

 should look for the plants from wind-sown seeds in other por- 

 tions of the wood, as well as in the blackberrj^ patch. That they 

 are not in the wood elsewhere permits us to say that the shade, 

 moisture, preservation of decaying leaves, or of some other inci- 

 dent not acceptable to other plants in the wood, but favorable to 

 these strangers, gave them the chance to sprout and grow. 

 They were, in fact, dependent on the blackberry for their 

 first start in life. This conclusion was further evidenced 

 by the fact that, though some of the annuals had evidently 

 seeded and reproduced plants for several successive seasons, no 

 plants were found spreading out of the protecting area of the 

 blackberry thicket. Certainly these species were all dependent 

 here on this plant, as this plant would probably be dependent on 

 others in some other instances. 



How some plants can exist, grow healthily, produce seed, and 

 not spread, Mr. Meehan illustrated in the case of Shortia galaci- 

 folia, the original locality of Michaux having a few months ago 

 been rediscovered b}'^ Professor C. S. Sargent. Though it had 

 maintained itself for the best part of a century, it had existed 

 without spreading. Some circumstance had evidently prevented 

 the seed from germinating, and these circumstances would 

 undoubtedly be controlled by the presence or absence of some 

 friendly plant. He offered the facts as a contribution to the 

 study of the interdependence of plants. 



October 26. 

 Mr. Geo. W. Tryon, Jr., in the chair. 

 Thirteen persons present. 

 The following was ordered to be printed : 



