520 SCIENCE PROGRESS. 



excitation of mucous cells is generally accompanied by out- 

 going " action current ". 



In the mammals (rabbit, guinea-pig and rat), nothing 

 definite was found as regards the action of digestive activity, 

 except that the " current of rest " tends to fall during the 

 earlier stages of digestion, and to rise towards the end. 

 Interference with the blood supply of the mucosa was found 

 to be a potent factor as regards the electromotive force of 

 the "current of rest". Complete cessation of circulation 

 causes speedy reversal of " rest current," while more moder- 

 ate interferences, such as that produced by dyspnoeic or 

 anaemic excitation of the bulbar vasomotor centre after 

 double vagotomy, or by excitation of the peripheral vagus, 

 all produce a drop in the electromotive force of the ingoing 

 current. Atropine, probably by cutting out the cardiac vagus 

 effect, prevents the fall of E.M.F. that results from vagus 

 excitation. Saline injections into the vascular system, ac- 

 companied by marked secretion and swelling of the mucosa^ 

 lead to a marked rise of the electromotive force of the 

 " rest current," and such current does not then fall rapidly 

 after death, as is normally the case. 



Bohlen considers that his results in cutting down the 

 ingoing current by diminution of blood supply, and in 

 raising it by causing excessive exudation of water into the 

 membrane, are in favour of Biedermann's idea, that the 

 "negative process" in the cell is the secretion of water. 

 Before passing to any further consideration of the respec- 

 tive theories of action already mentioned, a word must be 

 said as regards what is probably the highest development 

 of electromotive phenomena in glandular tissue. Fritsch 

 has maintained that the electrical organ of the fish Malap- 

 terurus is constructed of a mass of glandular cells, known as 

 "club cells," and derived originally from the overlying skin, 

 in which in the adult many are to be found. The theory is 

 extremely probable, but, unfortunately, as yet lacks embryo- 

 logical basis. 



These "club cells" are present in the epidermis in other 

 fish along with "goblet cells," and it has recently been 

 pointed out in the case of the skin of the common eel, that 



