748 BEPORT— 1892. 



From this it would appear that the p^roup usually breaks up when the fourth 

 frond has been produced, thus explaining the comparatively few groups of five 

 which are to be found. It would also account for the large number of pairs found 

 during this month, and perhaps for the fact that there are more than twice as 

 many pairs consisting of fronds with a right-hand bud as of pairs where the bud 

 k on the left ; for although the detaching of the right pair would temporarily 

 leave a left-handed pair, this would soon be altered by the left young frond 

 budding and pushing off the parent weed. 



After other remarks upon the tethering filament which appears at the base of 

 certain fronds in order to attach them loosely to the parent frond, and disappears 

 shortly after they are separated, with an account of experiments with duckweeds 

 grown in the dark, and others which continued to throw out buds, after being 

 tlivided in half, the paper concluded with the following questions presented for the 

 consideration of the botanical members of tlie Section : — 



1. As to the number of buds produced by a single frond of Lemna minor .'' 



2. The order and position of the buds ? 



3. The use of the connecting filament ? 



4. The absorption or destruction of the connecting thread after separation ? 



5. The explanation of the comparative number of fronds found connected, as 

 eliown in the table above ? 



Depahtmext of Physiology. 



I, Vital Absorption. By Professor E. "\Yayjiouth Reid. 



As a result of the researches of Dutrochet, the causation of the movement of 

 fluids through membranes in the animal body was considered to be entirely due to 

 osmotic action up till about the middle of the present century. The researches of 

 Briicke, Liebig, Ludwig, Graham, Fick, Eckhard, and others, bear witness of the 

 painstaking labour that has been spent upon the determination of osmotic equiva- 

 lents and diffusion rapidities. It was found, however, that with variation in the 

 kind of membrane used, and its state at the time of experiment, great variations 

 in the results made themselves manifest. In 1845 was publislied by Matteucci and 

 Cima a series of e.xperiments with skins of frog, eel and torpedo, and various mam- 

 malian mucous membranes, in which it was shown that, provided the membrane 

 was fresh, the direction of easier osmotic transfers varied with the facing of the 

 membrane towards the solutions employed for experiment, and it was found that 

 this peculiarity only existed so Ions* as the membrane was perfectly fresh. 



Later experiments with the bladder by Susini, using potassium ferrocyanide, and 

 Cazeneuve and Livon, using urea, have shown how greatly the phenomena of difl'u- 

 eion through the wall are etiected by the state of the lining epithelium. Tappeiner's 

 experiments upon the absorption of bile salts from the dog's intestine, and those of 

 Lannois and L(5pine upon the absorption of glucose and peptone, have pointed 

 clearly to the fact that the phenomena of intestinal absorption receive no clear 

 explanation upon the old osmotic hypothesis. 



Still more recently in Heideuhain's laboratory the work of Rohmann, and also 

 that of Gumilewsky, has done more to show the necessity of discarding the physical 

 ■explanation that so long seemed to meet the conditions of the case. 



The consideration, too, of the changes that are wrought upon substances in 

 process of absorption, such as the regeneration of albumen from peptone, pointed 

 out by Salvioli, Hoft'meister, and Neumeister, and the synthesis of fat when fatty 

 acid is supplied, demonstrated by Immanuel Munk, forces us to view the phe- 

 nomena of absorption in the organism from the vital and chemical rather than from 

 the purely physical standpoint. 



Three years ago, in experiments directed to determine how far the physiological 

 •condition of a membrane can affect the magnitude of an ordinary osmotic stream 

 caused to pass through it, I found, when using the skin of the frog freshly removed, 



