S02 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



into the tube. This oiicration may bo performed under the Microscope 

 if necessary. 



If any other movements are to bo imparted to the ovum an additional 

 apparatus is re(iuired. This is called the perforator, and consists of a 



Fia. 142. 



needle, its case, and motor apparatus — a lever controlling screw and 

 spring. The needles are made out of glass by drawing out very fine 

 threads from a glass rod over a lamp. A quantity of these about 10 cm. 



Fig. 143. 



long should be made. Those which are quite regular in thickness are 

 then to be arranged in packets, after inepccting them under the Micro- 

 scope ; the points are then fixed on to capillary tubes by means of a thermo- 

 cautery. This piece of manipulation requires much practice and patience. 



