80 NOTES AND MEMORANDA. 



der deutsclien Gesellschaft fiir Psychiatrie und gerichtlich Psycho- 

 logie.' The metliod of hardening is as follows, — observing that 

 differences exist in the treatment of the spinal cord, cerebrum, and 

 cerebellum. The spinal cord, after the careful removal of the dura 

 mater, is placed in spirit of from seventy-five to eighty per cent., 

 which is tinged a clear brown colour by the addition of iodine. After 

 from one to three days, during which the preparation must stand in a 

 cool temperature, the pia mater and the arachnoid are also removed, 

 the specimen remaining in the spirit, to which a few drops of iodine 

 must be added daily for three days, maintaining an ordinary tempera- 

 ture. It is then transferred to a three per cent, solution of chromate 

 of potass, and back again to the cool temperature. Here it hardens 

 thoroughly, which is known by the fluid becoming turbid, and by the 

 formation of a brown deposit upon the preparation. When this occurs 

 it must be immediately thoroughly washed with water, and immersed 

 in a solution of chromate of potass, from half to one per cent, strength, 

 in which it will not become too hard or brittle. Preparations of cere- 

 bellum can only be made when it has been taken from a perfectly fresh 

 body. Before immersing it in the iodine spirit, the vessels and mem- 

 branes must be carefully removed, especially at the vermiform process 

 and the " square lobes " ; and cotton wool should be stuffed into the sulci 

 on either side of the process, the rhomboidal groove, and the nates and 

 testes, should they be in the specimen, so as to render the passage of 

 the fluid into the deeper parts more easy. The preparations should 

 rest on cotton wool. The iodine spirit should be quickly increased iu 

 strength. After from seven to fourteen days the specimen should be 

 placed, provided it does not give to the finger, in a five per cent, solu- 

 tion of chromate of potass. The great brain, after being divided in 

 half through the length of the corpus callosum, is laid in weak iodine 

 spirit. After some hours the separation of the membranes in the 

 fissure of Sylvius, and at the tail of the corpus callosmn, should be 

 commenced, so as to allow of the permeation of the spirit. The pre- 

 paration must stand in a cool place (during summer in an ice-cellar). 

 After from ten to fourteen days it is removed to a four per cent, solu- 

 tion of chromate of potass. When sections are to be taken, it must be 

 washed carefully in water. Betz endeavours to avoid all rubbing of 

 the knife on the surface of the preparation, and sticking of the sec- 

 tion on the upper surface of the blade. To this end he has had con- 

 structed a knife whose upper surface is convex, the under one concave, 

 the radius of the lower one being somewhat smaller than that of the 

 upper. The blade is from one and a half to twice as long as it is 

 broad, the thickness being one-third of the breadth. For large cross- 

 sections, as for instance through the whole hemisphere, Betz uses a 

 knife whose blade is twenty-one centimetres (eight and a quarter 

 inches) long by ten centimetres (four inches) broad. This form of 

 knife (hatchet ?) makes it possible to keep the surface of the prepara- 

 tion and the section constantly wet by means of dropping spirit, so 

 that rubbing on the one and sticking of the other may be avoided. 



Stereoscopic Pictures of Objects seen with the Binocular. — Dr. J. 

 G. Kichardson stated at a recent meeting of the Academy of Natural 



