1894.] NATURAL SCIENCES OF PHILADELPHIA. 169 



some zymotic organism that permeates the whole structure of the 

 iudividual during its progressive growth. 



I have, in other papers, shown that the l)ark of trees is not 

 decorticated in any mechanical way, but by the growth of cork 

 cells, each species having its own time and manner of development. 

 In some trees these cells become active on bark but one or two years 

 old, while in the chestnut, Castanea, and some others it may be 

 twenty or more years before any sign of a "rough" bark appears, 

 through the quiescence of the cork cells. No one, as I have already 

 hinted, seems to have been able to demonstrate the causes whicli 

 lead to these varying and remarkable results. 



In the case of these holly leaves it is evident that they do not fall 

 in response to the requirements of any definite period of maturity, 

 but that the cork cells which provide for disarticulation are simul- 

 taneous witli the destruction of the parenchyma. This is apparently 

 the work of an adventitious agency, not essential to, but in some way 

 co-ordinate with the regular economy of the plant. 



On Bees and Honey-suckles. 



I was interested to-day, June 18th, in noting that while a few 

 honey bees persistently collected nectar from the mouths of honey- 

 suckles, by far the larger number collected from the fallen flowers 

 only. 



The plant was Lonicera japovica, in the two forms known in 

 gardens as L. brachypoda, and L. fiexuosa, both intertwining and 

 flowering together. I have, in the past, satisfied myself that a bee 

 which starts from the hive for pollen pays no attention to gathering 

 nectar, while the one looking for nectar collects that only. Whether 

 this is the course of labor for that trip from the hive only,or whether 

 these particular tasks occupy the whole day or more, may be an in- 

 teresting question. I had never noted bees collecting nectar from 

 fallen flowers ; indeed had not noted that fallen flowers had nectar, 

 so that the attention of the bees to them gave the subject a double 

 interest. 



The flowers are white when freshly opened, the next day yellowish, 

 the following they wither slightly and fall. Large numbers are col- 

 lected by the leaves on which they mostly lie till they turn brown 

 and shrivel completely. Those which were badly shrivelled seemed 

 preferable to the bees. 



