CIRCULATION IN PLANTS. 43 



vessels of animals. They are usually found con- 

 nected with the cellular parts of plants ; and, 

 possessing, as they evidently do, proper membranes, 

 they ought not to be regarded as merely enlarged in- 

 tercellular spaces. They are beautifully seen under 

 the microscope in the young stipules of various 

 species of Ficus, or Fig ; in the bractes of the 

 Calistegia sepkcm, or Bird-weed ; and in the petals 

 of the Papaver somniferum, or Poppy. They had 

 been seen by Grew, who termed them proper vessels. 

 Schultz, wlio observed them with greater care, 

 denominated them the vilal, or hitici/erous vessels, 

 and their fluid contents, the latex. We may also 

 discover, by the aid of the microscope, that this 

 latex is moving in currents with considerable ra- 

 pidity, as appears from the visible motions of its 

 globules ; thus presenting a remarkable analogy 

 with the circulation of the blood in some of the 

 inferior tribes of animals. This curious pheno- 

 menon was first observed in the Chelidonium by 

 Schultz,* in the year 1820; and he designated it 

 by the term Cyclosis, in order to distinguish it from 

 the true circulation of the nutrient fluids, which is 

 eftected in the higher animals ; and also from 

 another kind of circulatory motion, of a more 

 partial nature, of which I shall presently speak, 

 and which is termed rotation. 



The circular movement, or cyclosis, which has 

 been thus observed in the milky juices of plants, 

 has lately attracted much attention among botan- 

 ists : but considerable doubt still prevails whether 



* " Die Natur der lebendigen Pflanze." See also Annales 

 des Sciences NaUuelles, xxiii, 75. 



