( 154 ) 



it trorn tliis solvent. The warm solution soon deposits some plie- 

 nyliniide. 



To conclude we have found in comparative experiments that the 

 imides form the ethereal salts of amido-acids much easier with me- 

 thylic alcohol, than with aethylic- or propylic alcohol. The greater 

 ethereal saltforming faculty possessed by the former alcohol ') shows 

 itself eijually in those experiments. 



We herewith tender our best thanks to Messrs. van Breukele- 

 VEEN and VAN IIaaust, who assisted us with o-reat zeal in the 

 present investigation. 



Del ft /Amsterdam, October 1898. 



Physics. — „Description of an open manometer of reduced hci(jht'\ 

 By Prof. H. Kamerlingii Onnes. 



(Will be published in the Proceedings of the next meetingV 



Zoology. — „Cup-shaped red Jiloodcorpascles. (C/iromocraters/'. 

 By Dr. M. C. Dekiiuyzen. (Communicated by Ur. P. P. C. 

 Hoek). 



The red bloodcorpuseles of the lamprey (Petromyzon fluviatilis) 

 when examined living or after fixation, exhibit a remarkable shape, 

 which has escaped the attention of investigators. They are bell-or 

 cup shaped cells. Their body contains a rather deep cavity which 

 may be called an „oral invagination". The rather wide opening is 

 round, but owing to the facility with which the cells change their 

 shape, may become a split or a triangle. 



A second less evident „aboral" invagination is found at the aboral 

 pole, in a somewhat eccentric position however. Seen from above 

 one of the poles, the cell is somewhat oval, almost round. No 

 wonder that such a shape is not recognized, when the blood is 

 spread out in a thin layer, dried and then preserved. 



There is scarcely an object imaginable better calculated to make 

 the objections evident which must be alleged against the usual 

 methods of drying for the purpose of investigating the blood. 



True amoeboid properties are wanting; some of the damaged cells 



') Vid. Menschutkin. Lieb. Aiiii. 195, p. 357. 



