148 Walter Stiles 
the swelling of tissues as exemplified by frog’s muscle and sheep’s 
eyes. 
Miss D. J. Lloyd (1916) has also made a study of the swelling of 
excised stemo-cutaneous muscle of the frog in solutions of acids, 
alkalies and salts. She comes to the conclusion that the swelling of 
muscle both inside and outside the body is an osmotic phenomenon, 
and compares her results with those of Lillie (1907), who showed 
that acids and alkalies bring about an increase in the osmotic pressure 
of gelatine and egg-albumin. Miss Lloyd accepts the view that acids 
combine with colloids to give ionisable complexes which dissociate 
into a large “pseudo-ion” carrying a positive charge and a mobile 
ion with a negative charge; the degree of dispersity of the system is 
increased and so the osmotic pressure is raised (cf. Hardy, 1900). 
Similar considerations hold with regard to the action of alkalies. Miss 
Lloyd thus agrees with Procter (1914) in ascribing to ionisation the 
production of the internal osmotic pressure of such colloids, but 
differs from him in supposing that the colloidal ion is partly responsible 
for the osmotic pressure and not merely the mobile ion. In solutions 
of neutral salts and in sugar solutions (for the latter see Hardy, 1905), 
muscle may show a preliminary gain in weight, but sooner or later 
coagulation sets in and loss in weight supervenes (cf. Lillie’s results 
with gelatine, 1907). Miss Lloyd ascribes this to the suppression of 
the ionisation of the colloid particles of the muscle, which lose their 
charge and are coagulated. 
Miss Lloyd holds that there is no need to postulate the presence 
of a semi-permeable membrane surrounding the muscle fibres, the 
structure of the colloid in itself being presumably such as to prevent 
the movement of the colloidal ions and consequently also of the 
oppositely charged mobile ions. 
Loeb (1916) has suggested a causal link between the development 
of acidity in living muscle cells and the imbibition of water. It is 
suggested that the acid brings about a hydration of the proteins to 
such an extent that the true solutes are now held in a very reduced 
volume of water. This marked rise in osmotic pressure brings about 
the entrance of water into the cell. 
The observations of F. E. Lloyd (1915, 1916, 1917 a, 1917 b) on 
the effect of acids and alkalies on the growth of pollen tubes are of 
particular interest in the present connection. Lloyd grew pollen 
tubes in hanging drops of a solution of sucrose to which had been 
added a definite quantity of acid or alkali and made observations on 
the rate of growth of the tubes. In pure sucrose solutions the rate 
