Retrospective Criticism. 729 



In the Principles of Botany, paragraph 25., it is said that spiral vessels 

 " are not found in any part which is formed in a downward direction, and 

 are, consequently, absent from the wood, bark, and root." 



In the Principles of Horticulture, par. 15., we are told that " spiral vessels 

 are not found in the wood or bark, and rarely in the roots of plants." 



The former of these paragraphs lays down, as a positive rule, that spiral 

 vessels do not exist in the parts of plants which are formed in a downward 

 direction, and, as a consequence, that they are absent from the wood, bark, 

 and root. In the latter, it is said that spiral vessels are rarely found in 

 the roots. If they are ever found in these organs, does it not follow that 

 the principle which we are taught by the first paragraph is false ? 

 Principles of Botany, par. 25., " The function of the spiral vessels is 

 unknown. 

 33. Their functions (those of the ducts) have not been accurately deter- 

 mined. It is probable that they serve for the passage of air. 

 86. The medullary sheath consists of spiral vessels and ducts. 

 89. It carries upwards the fluid absorbed either immediately from the 

 earth, or through the intervention of the alburnum, and conducts it 

 into the leaves." 

 There appears to be a little " mystification " here. If the function of 

 the spiral vessels is unknown, and those of the ducts uncertain, how can 

 it be said that the spiral vessels and ducts, of which, as we are told, 

 the medullary sheath is composed, carry upwards fluid to the leaves i 

 Again, to make the matter clearer, it is stated in the 

 Princijyles of Horticulture, par. 21., that " Spiral vessels convey oxygenated 



air." 

 Principles of Botany, par. 200., " The food of plants consists of water 

 holding various substances in solution. The roots have the power 

 of separating these substances, and selecting such only as are con- 

 genial to the nature of the species." 

 Prmcij)les of Horticulture, par. 37., " These organs (the spongioles) have 

 no power of selecting their food, but will absorb whatever the 

 earth or air may contain which is sufficiently fluid to pass through 

 the sides of their tissue." 

 Will the learned professor reconcile these two principles? Other discre- 

 pancies might be pointed out in these two works, especially in the passages 

 relating to the excreting theory, against which it would be easy to adduce 

 evidence that would shake it to the very foundation. But enough has 

 been said to show the possibility of even such men as the learned professor 

 overreaching themselves, and also to justify my remark, that your unqua- 

 lified praises were, to say the least, premature. I am. Sir, yours, &c. 

 — A Journeyman Gardener. Nov, 1. 1832. 



We thank our correspondent for his strictures, and invite him to 

 continue them whenever he sees occasion. — Cond. 



Shalder's Fouiitain Pump. — As we strongly recommended this pump 

 (Vol. VII. p. 218.), we consider it right to lay before our readers the 

 essence of a paper, which we have received from our correspondent Mr. 

 Mallet of Dublin, on the subject. It appears that the person who has pur- 

 chased the patent right of this pump was endeavouring to sell that right 

 for Ireland to Mr. Mallet, who was disposed to purchase it, but who, being 

 rather surprised at the seller coming down very greatly in price, thought 

 of examining the records, and found, on consulting them, that there was 

 no patent for Shalder's pump, for Ireland, at all. Having detected this 

 attempt at imposition, he next thought of enquiring whether the invention 

 was a new one ; and he found it described in Belidor's Architecture Hy- 

 dralique, tom. ii. liv. iii. chap. iii. p.l20. ; and something very similar in 



