132 BANKS. 



used. Where overlapping parts occur it is an easy matter to release 

 them, pick them up from beneath and drop the bent pin where most 

 convenient for holding the tissue apart. '\%ile its own weight and the 

 adhesion of the base of the bent pin to the parafBne are amply sufficient 

 to hold the tissues apart, yet it can so easily be moved that there is 

 practically no danger of tearing important organs by an inadvertent 

 pull with the forceps, and in this lies the chief value of this method. 



I have found that organs as delicate and as intricately enmeshed in 

 trachea as are the ovaries or the abdominal nerve libers and ganglia of 

 Bombyx mori Linn., and Atiacus ricini Boisd., may be admirably dis- 

 sected by the use of the bent pin, whereas an attempt to hold them with 

 ordinary pins stuck into the paraffine would result in disaster to the 

 specimen. Another value of this apparatus is that it may be picked up 

 with the engaged tissue and moved here and there at w'ill and with 

 greater dispatch than if ordinary pins were used. There is also no 

 danger of pinning the part into the parafBne. 



Perhaps a no less useful feature of the bent pin is that it may be 

 used most successfully in glass vessels, e. g., Petri dishes, where obviously 

 no other method of holding tissues could be devised. 



This apparatus will be found particularly useful in the class room 

 or in' the anatomical laboratory where a lack of skill on the part of 

 students would be compensated for by a diminished • liability to spoil 

 specimens upon which hours of careful dissection had been spent. In 

 making the apparatus it is better to use the pointed end of the pin for 

 a hook, as the tissue can be more readily slipped off. 



Plate I shows several of these bent pins in use in the dissection of a 

 silkworm in a Petri dish. 



