the Vasa propria, and Receptacles of the Juices of Plants, 403 



then acquainted with the earlier researches of M. Schultz, he 

 adhered to the opinion that the laticiferous juices are of the 

 nature of secretions. 



M. Schultz specially studied the proper vessels of plants, and 

 enunciated various striking discoveries. He advanced the opinion 

 that the coloured juices of plants were no other than the nutritive 

 fluid j that this fluid is coagulable, and characterized by the pre- 

 sence of granules floating in a transparent liquid ; that it circu- 

 lates in thin, transparent, contractile vessels, without pores or 

 fissures, which ramify and anastomose together. The nutritive 

 fluid he called the latex, its containing vessels laticiferous vessels, 

 and its circulatory movement cyclosis. This movement he attri- 

 butes to the contractility of the walls of the vessels, and to the 

 properties of attraction and repulsion subsisting between the 

 granules and the walls of the vessels. The movement of attrac- 

 tion he terms autosyncrisis, and that of repulsion autodiacrisis. 

 Such plants as have no coloured sap have, he believes, a latex 

 analogous to that found in laticiferous ones, differing only 

 in its not possessing colouring granules. Moreover, he repre- 

 sents the laticiferous vessels as occurring in a state of expansion 

 when they are dilated and filled with granules, in a state of 

 contraction when they exhibit only a fine granular streak, and in 

 a state of articulation when they are gorged with juices, but are 

 divided, in consequence of advancing age, into sections by com- 

 plete septa. 



According to these views, plants possess a fluid analogous to 

 blood, and a circulatory apparatus resembling the vascular system 

 of animals. 



The statements of M. Schultz produced a great sensation at 

 the time of their publication among botanists, by many of whom 

 they were accepted as true. However, his hypothesis was very 

 soon keenly attacked, and its foundations disputed, by Mohl, 

 Meyer, Treviranus, and others. Mohl denied the existence of 

 the molecular movements of the globules of the latex (the auto- 

 syncrisis and autodiacrisis), and also the phenomenon of cyclosis. 

 According to him, any onward movement that may be observed 

 in the liquid within the pi'oper vessels of a plant is not a normal 

 condition, but a consequence of a wound or section of the tissues 

 permitting an escape of their fluid, or else of pressure, of heat, 

 &c., whereby the liquid is driven from one vascular ramification 

 into another. Lastly, the very existence of vasa propria has 

 been denied, and the structures so called have been asserted to 

 be merely passages or channels which, as a secondary phase of 

 growth, acquire distinct walls ; at the same time, the analogy 

 of the latex with the blood of animals has been disowned ; and 

 these various objections have induced many botanists, who at 



