VOL. XXXVI,} PHILOSOPHICAL TRANSACTIONS. 410 



52' in the exening; emersion, 11*' 42™ 20^ in the evening; immersion total, 

 Feb. 22^* 9*^ 42™ 30' in the evening; Oct. Q'' 6^ 6™ SO" in the morning. 



ji Lunar Eclipse observed at Pekin, ^ug- IQ, 1728, N.S. By the same. 

 N° 414, p. 368. 



At 10*^ 54™ correct time, the penumbra began ; 1 1*" 2™ the true eclipse began; 

 11*^52™ the moon's centre immerged; 12'' 31™ the middle, the quantity 7t 

 digits; iS'' 10™ the moon's centre emerged; 14*' the eclipse ended. 



On the Veins and Arteries of Leaves. By Frank Nicholls, M. D. F. R. S. 

 N°414, p. 371. 



By a letter from Dr. Fuller in Holland, the society was informed, that pro- 

 fessor Ruysch had observed something, in dissecting leaves, analogous to the 

 veins and arteries of animals; but without explaining in what manner these 

 different vessels were disposed, or by what means they may be distinguished 

 from each other. 



When Dr. Nicholls examined the collections of Frederick Ruysch and Albert 

 Seba at Amsterdam, in both which was a great variety of dissected leaves, they 

 made no mention of such a discovery; though in a leaf from the collection of 

 Ruysch he could, with a glass, observe the fibres to be double towards the edges 

 of the leaf, which at that time he imagined to be an unnatural division of the 

 fibres, as in decayed sticks. 



In the mean time, Albert Seba having communicated the method of dis- 

 secting leaves to the society. Dr. N. separated the pulpous from the fibrous 

 parts of several leaves after his method ; when examining them by glasses and 

 in water, he found that each fibre was naturally separated into two distinct 

 fibres, by a thin stratum of the pulpous substance; and that this separation was 

 continued through all the fibres and stem of the leaf, so as to form two distinct 

 planes of similar net-work. 



Though this duplication of the vessels in leaves, seems to point out an ana- 

 logy between them and the veins and arteries of animals, yet the Doctor sees 

 no probable means of guessing which are the arterial and which the venal 

 fibres. 



That he might illustrate this matter, he prepared two leaves, the one of an 

 apple, the other of a cherry, in which, both the separation of the fibres and 

 stem, and the pulpous substance, by which they are naturally separated, are 

 very obvious. See plate xi, where fig. 1 shows the cherry leaf, and fig. 2 the 

 apple leaf, their planes being separated. 



3u 2 



