498 



filaments, the hyaline or inter-reticular substance being passively moved, 

 the opinion which had been previously enunciated by Leydig to the 

 effect that the inter-reticular substance or hyaloplasm produces the 

 amoeboid movements by flowing in one or other direction is probably 

 correct; and further that a similar explanation of the contraction of 

 muscle must also be adopted as the result of a comparison between 

 the structural appearances of the extended and contracted muscle 

 fibril, I proceeded to point out that although we had at that time 

 no clear evidence regarding the structure of vibratile cilia, nevertheless 

 by far the simplest explanation of their action and one which did not 

 stand in contradiction to any known fact is to assume that they are 

 hollow extensions of the cell, occupied by hyaloplasm and invested by 

 a delicate membrane, thickened (or at any rate less extensible) either 

 along one side or in a spiral line. If this assumption were correct, 

 then any tendency of the hyaloplasm of the cell to flow into or out 

 of such hollow process, in other words to increase or diminish the 

 tension within it, must result in a bending movement if the line of 

 less extensibility were a straight one; or in a cii'cular or corkscrew 

 movement if the line were a spiral one. And since the amoeboid 

 movements of cell protoplasm are in all probability flowings of the 

 hyaloplasm due to local changes in tension at the surface of the cell 

 this assumption regarding the structure of cilia would at once bring 

 their action into line with that of other more general contractile 

 manifestations of protoplasm. 



In the volume of Asher and Spiro's Ergebnisse der Physiologie 

 (Jahrg. 2, Abteil. 2) which has recently been published, A. Pütter in 

 an article, entitled "Die Flimmerbewegung", pours out the vials of his 

 contempt upon what he is pleased to call this "theoretic curiosity". 

 "Man sieht", says he, "daß es um so leichter wird, Theorieen, oder 

 sagen wir lieber luftige Gedaukenbauten aufzuführen, je weniger man 

 sich an die oft so spröden Tatsachen hält!" But Dr. Pütter himself 

 proceeds, a little later in his article, to formulate a theofy of ciliary 

 action which, apart from being physically unthinkable, is based entirely 

 upon hypotheses; and, as I shall proceed to show, is not only un- 

 supported by fact but is directly contradicted by such facts as have 

 accumulated both before and after the date of the promulgation of the 

 theory which he so cavalierly condemns. Quis tulerit Gracchos de se- 

 ditione queren tes? 



It is said that wherever a plant of poisonous character is to be 

 found beneficent nature provides in its neighbourhood another which 

 will yield an antidote, and the painstaking article in which Dr. Pütter 



