OBSERVATIONS ON THE STRUCTURE OF PROTO- 

 PLASM BY AID OF MICRODISSECTION. 



WILLIAM SEIFRIZ. 



TECHNIQUE. 



The introduction of the Barber pipette holder brought into 

 use an exceedingly ingenous technique which promises to open 

 up a great field of research, in which not only many of the results 

 got from fixed material can be confirmed or refuted, but in which 

 observations on the structure and behavior of living protoplasm 

 can be made with an accuracy and certainty not otherwise pos- 

 sible. This instrument, originally designed to hold miniature 

 pipettes for isolation and injection work, is equally well adapted 

 for the manipulation of glass dissection needles. Each needle is 

 held in a three-movement clamp and extends into a small moist 

 chamber placed on the stage of the microscope. The vertical 

 needle-tips project up into a hanging drop in which the material 

 to be dissected is suspended. 



A description of this instrument and of the technique connected 

 with it was first published by Barber (1914). Chambers (1915) 

 has given a brief account of its use, and later (1917^) published 

 a full description of the instrument and of the ways of making 



micro-needles. 1 



LITERATURE. 



The literature published on microdissection studies is limited 

 practically to the articles of G. L. Kite and Robert Chambers. 

 Both of these men employed a Barber instrument essentially 

 identical with that used by the writer. A list of their publica- 

 tions is appended to this paper. 



TERMINOLOGY. 



A serious difficulty encountered by the investigator in this 

 field is the limited vocabulary which is at his disposal for the 



1 It is of great importance in making sharp needles to have a minute flame. 

 A very satisfactory micro-burner can be made as was suggested to the writer by 

 Dr. E. E. Free from the smallest size (no. 27) hypodermic injection needle by 

 snipping off the bevelled end with sharp shears. 



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