( 53 ) 



Such warming and cooling can be repeated a couple of times, 

 whilst in proportion to this the number of reflections continues 

 varying, provided the muscle be not for too long a time exposed to 

 too high a temperature, as in this case a clearly perceptible perma- 

 nent hardness will show itself. 



Physiology. — "On the structure of the ganglion-cells in the central 

 nervous system of Brauchiostoma lane." (Second communie.) 

 By Dr. J. Boeke. (Communicated by Prof. G. C. J. Vosmaer). 



(Communicated in the Meeting of May 31, 1908). 



a. The infundibular organ. 



The cells of the differentiated part of the ventral cerebral wall of 

 Brauchiostoma, which I described some years ago in these Pro- 

 ceedings x ), and which was then called the infundibular organ on 

 account of its place and the homology that could be drawn from 

 that, are quite different in their structure from the other cells, of 

 which I gave a description in my former paper 2 ). 



Among the authors, who in recent years have published researches 

 on the central nervous system of amphioxus, Kupffer 3 ) gives the 

 same description of the cells as I gave in my paper in 1902, and 

 only mentions the organ as consisting of long cylindrical cells with 

 curved cilia and a clear hyaline protoplasm. Kupffer homologises 

 the differentiated epithelium with the tuberculum posterius of the 

 craniote embryos. Joseph 4 ) only mentions the organ without adding 

 anything to the description. Edinger 5 ) who examined preparations 

 stained after the method of Bielschowsky, calls it "das aus grossen 

 Flimmer- und Sinneszellen bestellende Infundibularorgan", without 

 mentioning on what is founded the opinion, that there are two kinds 

 of cells to be found. In the drawings reproduced in his paper nothing 

 is to be seen but a faint striation of the ventral wall of the brain 

 at the place of the infundibular organ. According to Wolff 8 ) there is a 

 striking resemblance between the differentiated epithelium of the 

 infundibular organ and the gelatinous tissue that we find in the 



x ) Proc. Roy. Acad of Sc. of Amsterdam, Math. Phys. Gl. Meeting of April '07 

 p. 86. 



2 ) Proc. Roy. Acad, of Sc. of Amsterdam, Math Phys. CI. Meeting of April '02 

 p. 695. 



3 ) Handbuch der Entwickelingslehre (Hertwig), Vol. 2, 3d part. 



4) Verhandl. d. Anat. Gesellsch. 18. Vers. 1904. 



5 ) Anat. Anzeiger, Bd. 28, 1906. 



6 j Biol. Centralblatt. Bd. 27, 1907. 



