HOLMESDALE NATURAL HISTORY CLDB. 17 



to destroy insects in the immature state probably has its effect in 

 abnormally developing some of those which survive and emerge as 

 perfect insects. He further referred to the great abundance of the 

 Tineinse or Clothes Moths as one peculiar feature of the year. 



Evening Meeting, Dec, H/'A, 1877. Dr. Bossey read a paper 

 on the Circulation of the Sap in Plants. He spoke first of the 

 structure of the fibres of the root, and of the action that takes place 

 when they come in contact with the moisture of the soil, the first 

 absorption being due to Endosmosis, the upward movement of the 

 fluid being afterwards aided by capillary attraction. He also 

 explained in detail the other causes which operate to produce the 

 ascent of the sap, and the modifications it undergoes in its progress, 

 and especially when it circulates through the leaves of the plant, 

 where it loses a large part of its water by evaporation during the 

 day, and receives the addition of hydro-carbons formed from the 

 decomposition of water and carbonic acid, and is then fully prepared 

 to supply nutrition and tissues to the plant. Dr. Bossey then re- 

 ferred to the descent of the sap, a process which although denied by 

 many modern physiologists, he considered had been fully established 

 by observation and experiment. Taking this view, he spoke of the 

 causes which conduce to its descent, including the contraction of 

 the leaves at night owing to the lower temperature, also the abundant 

 absorption of water at the same time through the cuticle and hairs 

 of the leaf; and when it descends further, flowing between the bark 

 and wood, capillary attraction and gravitation both operate to accel- 

 erate its descent. During its downward course it is continually drawn 

 off on the one side by the medullary rays to supply nourishment 

 to the wood, and on the other to maintain the growth and substance 

 of the bark; this constant demand upon its volume contributes to 

 cause a further flow from above downwards, and may indeed be 

 considered as the main cause of its descent. Dr. Bossey then 

 adduced various facts in support of the views taken in his paper ; for 

 instance, if a stem with colored juice be cut, the lower surface of 

 the cut is seen to give but little juice as compared with the upper. 

 BerthoUet says that people in the Canaries tear off the bark of a 

 poisonous Euphorbia and then suck a limpid and harmless sap from 

 the stem. Increase of wood may be prevented by cutting off an 

 •nnular portion of bark; and the same occurs if a brass plate is 

 placed between the bark and the wood, wood being then formed 

 only outside the plate. The success of budding trees depends on 

 the same circumstance, the tongue of inserted bark conveying sap 

 to the inserted bud. If a stem be tightly girt by a ligature it swells 

 and forms new wood above the band, and scarcely increases in 

 diameter below it. De la Baisse caused a Euphorbia to pump up 



