238 THE ZOOLOGIST. 



Glyciphagus domesticus and G. spinipes. After describing in detail observa- 

 tions and dissections extending over three years, the author concludes that 

 there is a hypopial stage in the life-history of Glyciphagus, but far less 

 developed than in Tyroglyphm, and not an active stage in the species 

 observed ; that it does not occur to all individuals of a species, and it has 

 not been ascertained whether it occurs in all species ; that the stage is not 

 the result of dessication, or unfavourable conditions ; and that it occupies 

 the period between the penultimate ecdysis and that immediately previous. 

 Dr. C. Stewart having criticised Mr. Michael's researches in favourable 

 terms, a communication was made by M r. C. B Clarke on " Root-pressure." 

 He contested the view of A. Sachs (and his followers) that root-pressure is 

 sufficient to sustain the weight of a column of water of the height of 100 (or 

 even 300) feet, and to force out drops at particular points of the leaves. 

 He maintained that it was a mathematical error to apply the equation 

 p = g pz to the case of water in plants, and that in a collection of cells 

 and longitudinal tubes of varying size (all very small) the only mechanical 

 ideas that could be applied were those of capillary attraction and motion. 

 In the discussion which followed, Prof. Marshall Ward thought root-pressure 

 necessary to explain the admitted results of manometer experiments ; 

 Mr. A. W. Bennett, on the other hand, regarded the assumption of a high 

 fluid-tension in the cells of roots to drive moisture to the summits as 

 nothing more than an expression of our ignorance as to what the water 

 does move. 



A paper, " On the Ovicells of some Lichenoporse," having been read by 

 the Zoological Secretary, Mr. W. Percy Sladen, in the absence of the author, 

 Mr. A. W. Waters, the meeting adjourned to May 24th, 



Zoological Society of London. 



April 17, 1888.— Dr. St. Geokge Mivart, F.R.S., Vice-President, 

 in the chair. 



The Secretary read a report on the additions that had been made to the 

 Society's Menagerie during the month of March, 1888. 



Dr. G. Stewart exhibited a preparation showing the structure and 

 development of the brood-pouch of a Marsupial Tree-Frog, Nototrema 

 marsupiatum. 



Mr. Boulenger exhibited and made remarks on the type specimen of a 

 new species of Marsupial Tree Frog, Nototrema fissipes, recently discovered 

 by Mr. G. A. Ramage, near Pernambuco, in Brazil. 



Mr. Herbert Druce read the descriptions of some new species of 

 Heterocera collected by Mr. C. M. Woodford at Suva, Viti Levu, Fiji 

 Islands. The collection had been made during the months of February, 

 March, and April, 1880, and was especially interesting on account of the 



