Schleiden in reply to Mohl on Annular Vessels. 25 



a spiral organization is the ordinary and normal state in the 

 secondary layers of the vessels ; but it is not the only state 

 to be found there. Annular organization occurs as a pri- 

 mary formation, and presents in some degree an intermediate 

 form between the spiral wound to the left and that wound to 

 the right. Moreover, reticulated organization is also found 

 primitively, sometimes more nearly resembling the pure spi- 

 ral, and sometimes the annular form. 



Consequently, my researches on annular vessels afford op- 

 posite results to those of Schleiden. Nevertheless, I am far 

 from pretending that he has observed badly ; on the contrary, 

 he appears in these researches as a skilful phytotomist, and 

 as one experienced in the use of the microscope ; but I think 

 his interpretation of what he saw to be far from exact, inas- 

 much as he has considered accidental though persistent vari- 

 ations of form as normal, transitory and necessary stages of 

 the metamorphosis. 



V. — Preliminary Reply to MohPs Essay on the Structure of 

 Annular Vessels. By Dr. M. J. Schleiden*. 



M. Mohl has answered my challenge more speedily than I 

 could have expected, and published his remarks in opposition 

 to my late treatise. These relate only to my views regarding 

 the origin of annular vessels. It is to two points especially 

 that I purpose at present to call attention. 



I am almost ashamed to mention the first, viz. MohPs cor- 

 rection of my notion, that the crossing of the pore-like fis- 

 sures depends upon the apposition of oppositely turned spi- 

 rals. The thing is so simple, that I scarce understand what 

 demon of thoughtlessness possessed me when I entertained 

 the notion ; and, in spite of the mortification of being caught 

 in so marvellous an hallucination, I thank him from my very 

 heart for having in so friendly a way rid me of this goblin. 

 I should scarcely deem it necessary to mention the matter at 

 all did I not consider it the indispensable duty of every con- 

 scientious inquirer to retract openly and expressly every 

 known error, as the so doing is the only surety that he is in- 

 deed anxious for truth. 



The other point concerns the main subject itself. The hi- 

 story I gave of the development of annular vessels respected 

 only the simplest case, that of rings arising from a single 

 thread ; and I feel confident that I have not deceived myself 

 in the cases alleged, since my researches were made on ves- 



* Translated from Flora, 1840, p. 1. Communicated by the Rev. M. J. 

 Berkeley. 



