Dissection and Injection of Living Cells. 387 
Other investigators that I know of who have devised instru- 
ments for micro-operative work are Schmidt (1869, 1870), Birge 
(1882), Chabry (1887), Schouten (1905, 1911), Tchahotine (1912- 
1921), McClendon (1907), Malone (1918), Bishop and Tharaldsen 
(1921). 
Schmidt’s instrument is one of historic interest only. 1 have 
already described it (1918). Chabry used a delicate spring device 
with which he could shoot the tip of a glass needle into an ovum 
to any desired depth. Schouten uses his for the isolation of 
bacteria. It consists of a pillar carrying a needle which may be 
mechanically raised and lowered. For the horizontal movements 
Schouten depends upon pushing the microscope on its base. 
McClendon attached an up and down movement to a Spencer 
mechanical stage. Tchahotine used a mechanism attached to the 
tube of his microscope from which extended a glass needle curved 
in such a way as to bring its tip into the field of a low-power 
objective where it was brought into focus. Dissections of cells are 
carried out by moving the microscope tube and by pushing the 
cells against the needle tip by means of the mechanical stage of 
the microscope. Malone uses Schouten’s method, but, instead of 
having a special pillar with a raising device, he mounts his pipette 
carrier on the tube of a second microscope, whose adjustments 
serve as a means for raising and lowering the pipette. Bishop 
and Tharaldsen have a simple instrument based on a principle 
somewhat resembling mine, but lacking in proper control for one 
of the two lateral movements. 
Recently I have heard that Zeiss is manufacturing a micro- 
dissection instrument, which, however, is said to be of an intricate 
design. 
Tchahotine and Bovie have recently devised a method for pro- 
ducing localized injury to a cell by means of ultra-violet rays. 
The method is very ingenious, but, of course, is rather limited in 
its application to micro-dissection. 
Bibliography. 
Barber, M. A. (1904). — A New Method of Isolating Micro-Organisms. 
Journ. Kans. Med. Soc., iv. 487. 
— — (1911). — A Technic for the Inoculation of Bacteria and other Substances 
and of Micro-Organisms into the Cavity of the Living Cell. Journ. 
Inf. Dis., viii. 848. 
(1914). — The Pipette Method in the Isolation of Single Micro- 
Organisms and in the Inoculation of Substances into Living Cells. 
The Philippine Journ. Sc., Sec. B, Trop. Med., ix. 307 (reviewed in 
Zeitschr. wiss. Mikr., Bd. 32, S. 82, 1915). 
Bishop and Tharaldsen (1921). — An Apparatus for Micro-Dissection. 
Amer. Nat., lv. 381. 
Chabry, L. (1897). — Contribution a V Embry ologie normal et Teratologiques 
des Ascidies simples. Journ. de l’Anat. et de Physiol., xxv. 167. 
