$62 ELEMENTARY ORGANS. CHAP. III. 



he had perceived a sort of vermicular and sponta- 

 neous movement in them. But as I believe, he 

 thought he saw this movement only once, and as 

 it has never since been seen by any subsequent ob- 

 server, it appears that we must be content to set it 

 down to the score of microscopical deception, or to 

 the effect of the atmosphere upon the tubes when 

 exposed to its action. 



ARTICLE 4. False Spiral Tubes. The false spiral 

 tubes are tubes apparently spiral on a slight in- 

 spection, but which, upon minute examination are 

 found to derive their appearance merely from their 

 being cut transversely by parallel fissures. They 

 Not ca- cannot consequently be uncoiled like the true spiral 

 King un- tu bes ; nor can they be separated into distinct 

 led - rings ; because the continuity of the membrane 

 of which they are formed, and by consequence the 

 extremities of the fissure which may always be 

 discovered by a little attention, prevent that sepa- 

 ration. They are somewhat analogous to the porous 

 tubes; for the fissures, like the pores, are furnished 

 with a ring surrounding the lip. But they are more 

 generally found in the soft parts of woody plants 

 than the porous tubes, and often also in herbaceous 

 plants. In the Lycopodia and Ferns, they are 

 found in great abundance ; and also in the soft 

 parts of the vine.* I have often observed them in 

 vine shoots of about a year old ; but not far from 

 the pith ; which makes me suppose that they are 



* Mirbel, Phys. Vrg. vol. i. p. 65. 

 4 



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