330 PROTOPLASM 



outset in places, or whether after the constriction of the cell 

 the state of things that exists at the ends of the normal cell 

 is quickly restored at the ends of the constricted pieces, as 

 the result of a kind of regeneration, all this may remain an 

 open question, in order not to multiply further the number 

 of assumptions and possibilities. 



However indecisive the results may be which we have 

 obtained with regard to the explanation of the rotation cur- 

 rents, it is nevertheless obvious from the preceding discus- 

 sion that this case appears, under certain conditions, to 

 admit of an explanation based upon our conceptions of the 

 structure and the motor phenomena of protoplasm. 



A few words in conclusion to this work. Unfortunately 

 this Memoir has, while in course of preparation, consider- 

 ably exceeded the limits originally prescribed for it, although 

 I have taken pains to be as brief as possible, even at the risk 

 of being somewhat difficult to understand in those questions 

 which have hitherto lain beyond the province of biologists. 



It gives me great pleasure to seize the opportunity of 

 expressing my heartiest thanks to all those who have helped 

 me in this work by their kind assistance. To my esteemed 

 colleagues at Heidelberg, Professors Askenasy, Horstmann, 

 Kiihne, and Quincke, I am greatly indebted for much advice, 

 and also to a great extent for assisting me with books and 

 apparatus. I am similarly obliged to the juniors in my 

 Institute, especially to Herrn Blochmann, von Adelung, von 

 Erlanger, Hilger, Lauterborn, and Schewiakoff, for much 

 assistance in the course of the last few years. During a 

 short stay at the Zoological Station at Naples in the year 

 1890, the work I had in hand was greatly promoted by 

 the most friendly attention to my wants. 



All those whom I have named I beg again to accept of 

 my most cordial thanks. 



