WENHAM, ON THE SAP-CIRCULATION OF PLANTS. 



49 



n-r> 



seen to be adherent. Some are but recently deposited, while 



the underlying ones are in various regular 



stages of transition, gradually losing their 



form and outline, and finally all traces of 



individuality become lost ; and by a species 



of induration the particles become united 



and identified, with the solid body of the 



spine. 



In very many specimens of this object 

 that I have submitted to examination, the 

 deposit has been so rapid, that there was 

 not sufficient time for the complete con- 

 densation of the component corpuscles. 

 In these instances a number of them have 

 been caught and loosely enclosed in one 

 or more cavities, as shown at d d, and, 

 with the exception of being perfectly 

 motionless, the contained corpuscles are 

 the exact counterpart of those circulating 

 in the spine. The walls of the containing 

 cavities do not possess a definite outline, 

 because they are lined with corpuscles in 

 all their transition stages. 



I have now brought forward the chief 

 substance of my notes on this subject ; 

 they were made without previous study, 

 and with an intention to avoid all hypo- 

 thesis, and to confine myself to as clear a 

 description as I could give, of any facts 

 that the microscope might reveal. 



There is yet very much to be learned 

 respecting the sap-circulation of plants, 

 particularly in their different organs ; but 

 the inquiry is attended with much difficulty, 

 from the necessity of our being compelled 

 to examine detached and lacerated specimens. In many ex- 

 amples this is not of material consequence, as in some aquatic 

 plants, for in these the cells retain their independent motions 

 and individuality, long after their separation ; but in non- 

 aquatic plants the case is somewhat different, for the mutual 

 dependence of neighbouring cells is so considerable, that in 

 many instances, death is the immediate result of detaching 

 them, and the movements immediately to be seen under the 

 microscope, are probably only the lingering remnants of 

 vitality, and do not perfectly represent the circulation in the 

 uninjured plant. 



VOL. IV. E 



