122 ROBERT CHAMBERS. 



War, during which his drawings and manuscript were burned in a 

 conflagration in Washington. In his later paper he has two 

 illustrations showing a liver cell being torn in two by needles. 



In 1887 Chabry described an apparatus in which a glass 

 needle was held in a sheath in such a way as to allow the needle 

 to be pushed to any prescribed distance into the bore of a glass 

 capillary tube. The bore of the capillary was made just large 

 enough to admit a single ovum and hold it in place. By proper 

 adjustments, the needle could be pushed to any depth in the 

 ovum. The apparatus was placed on the stage of a microscope 

 and Chabry was able to injure locally a Strongylocentrotus ovum 

 while under observation. Chabry's instrument has been used 

 for experimental embryological work and is described in detail in 

 Ehrlich's " Enzyklopadie fur microskopischen Technik," 1910. 



In 1907 J. F. McClendon first described his "mechanical 

 finger," which consisted of an ordinary Spencer mechanical stage 

 with an additional screw to allow of movements in three different 

 directions and a clamp to hold a needle or pipette. With this 

 apparatus, McClendon was able to suck the nucleus out of a 

 Chatopterus egg. In 1909 he described an improved form with 

 which he dissected certain Protozoa. 



In 1912 an apparatus was described by Tschachotin. It con- 

 sists of a clamp attached to the side of the objective of a micro- 

 scope. In the clamp is fastened a needle which curves so as to 

 project under the objective and is so adjusted that the tip lies in 

 the focus of the objective. The needle point is lowered into the 

 object to be dissected simply by bringing the object into view 

 under the microscope and lateral tears are made on moving the 

 object with the slide by means of the mechanical stage. 



In 1904 Barber first described his method of using a hanging- 

 drop in a moist chamber for isolating microorganisms. A fuller 

 account appeared in 1997 in which he first describes a mechanism 

 for holding micropipettes and where he mentions Montrose T. 

 Burrows as having assisted him much in its design. Elaborations 

 of his instrument appeared in his papers of 1908 and 1911. In 

 1911 he suggested the possibility of the use of his instrument for 

 cell dissection and for investigation on fertilization and heredity 

 problems. His paper of 1914 is a detailed and precise descrip- 



