140 PRINCIPLES OF GENERAL PHYSIOLOGY 



An experiment by Calugareanu (1910, p. 101) shows that lecithin does not distribute it.-dt 

 between water and chloroform according to the usual rules of relative solubility. If chloroform 

 be shaken up with an equal volume of a '5 per cent, watery lecithin "solution," instead of 

 the lecithin oeing extracted by the chloroform, in which it is greatly more soluble than in 

 water, what happens is that the chloroform layer only contains 8 per cent, of the total lipoid 

 present, the rest is still present in the watery phase, but has taken up 50 per cent, of the 

 chloroform. No doubt this behaviour is connected with the state of the lecithin as an emulsoid 

 colloid, especially in presence of chloroform. 



It is scarcely necessary to remark that, as yet, it is not possible to explain 

 satisfactorily why changes of permeability should give rise to the various 

 phenomena connected with the state of excitation or of narcosis ; further 

 investigation is required and it seems probable that a more intimate knowledge 

 of the electrical conditions of the surface of the cell will give valuable information. 

 We have seen (page 120) how the impermeability of the membrane to one only of 

 the ions of a salt prevents the escape of the other, diffusible, ion, giving rise 

 to a difference of potential between the two sides of the membrane, and how 

 this can be changed by the presence of salts of which both ions are diffusible. 

 But whether such changes in the polarisation of the membrane are sufficient 

 to account for the change in permeability, as Lillie appears to hold, or whether 

 the change in permeability is itself the primary factor, will come up for discussion 

 later in Chapter XIII. 



The effect of the substances to which Armstrong (1910) has applied the name " hormones " 

 is clearly allied to the increase of permeability produced by fatal quantities of anaesthetics. 

 These " hormones " are lipoid-soluble and coincide very closely with those substances which 

 are known to abolish the semi-permeability of the membrane, such as ether, alcohol, toluene, 

 etc. Their main obvious action is to set up an enzymic process which was previously in 

 abeyance, such, for example, as the action of emulsin in the leaf of the cherry-laurel on a 

 cyanogenetic glucoside also present. This is regarded by Armstrong as being due to an 

 exciting action on the part of the " hormone" after entering the cell ; but it seems to me that 

 it falls T>ettr into line with other similar processes if it be looked upon as due essentially to 

 the removal of some such obstacle as that of a membrane, which prevented the access of the 

 enzyme to the glucoside. 



ffcemolysis is of two kinds. One in which the surface membrane of the 

 corpuscles is acted on by various haemolytic agents, such as saponin, the other 

 in which the corpuscle is broken up by osmotic swelling, as in the action 

 of water. Substances acting on lipoids produce the first effect ; hypotonic 

 solutions, the second. 



Ryvosh (1913) holds, with Hamburger, that, in haemolysis by hypotonic solutions, the 

 membrane is not destroyed, but merely stretched to such a degree that the pigment can 

 escape. The ground for this view is, that, after treatment with water, or with 0'3 per cent, 

 sodium chloride, although the relative volume of the deposit, after centrifuging, is 0"2 in the 

 first case as against 0'8 in the second, yet, on placing in 2 per cent, sodium chloride and again 

 centrifuging, the volumes became practically equal, 0"2 to 0'25. That is, although the 

 corpuscles were greatly swollen in 0'3 per cent, sodium chloride, they could still contract 

 under the influence of a hypertonic solution, showing that they retained their semi- 

 permeability as regards sodium chloride. 



Further details are beyond the space at our disposal and may be obtained 

 from the general summary by Stewart (1909). 



Secretion. It is clear that constituents formed in gland cells must leave 

 these cells by the side turned towards the lumen of the alveolus in connection 

 with the duct. Apart from the actual chemical processes in connection with 

 secretion, to be described in a subsequent chapter, changes in the permeability 

 of the cell membranes must be taken into account. Various researches by 

 Asher and his co-workers have brought out a number of facts, interesting in 

 this connection. It is well known that atropine has the property of stopping 

 the activity of secreting cells in general, and Garmus (1912) shows that, under 

 the action of this alkaloid, the cells of the glands of the frog's skin take up less 

 dye than normally. There is no reason to suppose that the actual stainable 

 material is diminished, so that the result must be ascribed to a diminution "of 

 permeability, especially as pilocarpine, which excites the cells, has the opposite 

 effect on staining. We saw previously that, in the excited muscle cell there is 

 also an increase of permeability. It has been shown by Straub (1912, p. 22) 

 that the action of atropine in antagonising that of muscarine on the heart is 



