12 IRVING HARDESTY 



Vials, with blank labels on them, and a supply of fixing fluids 

 were taken to the slaughter-house and the cochleae were dropped 

 into fixing fluid as they were removed, the name of the fluid 

 and the stage of the specimens being then indicated on the label. 



A series of developing cochleae were finally obtained, be- 

 ginning with those of fetuses of 3.5 cm. in length (crown rump 

 measurement) and increasing by from 1 to 3 cm. up to fetuses 

 at term. The latter stage varies in length between 20 and 30 

 cm. and had to be judged by the appearance of the fetus, chiefly 

 ])y the amount of the hair on the body and the condition of the 

 eyelids. The head of the fetus was removed and split sagittally, 

 the brain cleaned out and, in the older specimens, the cochleae 

 were broken out with the fingers. In the younger specimens, 

 a square of the skull containing the cochleae was cut out, the 

 surplus external tissue removed and the square dropped into 

 fixing fluid. From certain of these, the cochleae could be re- 

 moved under the dissecting microscope upon return to the labo- 

 ratory; others, the youngest, were best carried through the pro- 

 cedure and sectioned entire, the plane of section determined by 

 the landmarks of the cranial wall. 



Specimens for the study of the adult tectorial membrane in 

 the fresh conditions were placed in amniotic liquor, brought to 

 the laboratory and used immediately. Occasionally physiologi- 

 cal salt solution was used to which had been added a few drops 

 of saturated solution of the bichloride of mercury, to check 

 maceration. However, only sufficient fresh specimens were used 

 to obtain a few sets of observations of the fresh tectorial mem- 

 brane, it having been found in the previous study and verified 

 here that certain fixing fluids, in themselves, distort the mem- 

 branes very little if at all, and that the membranes may be re- 

 moved much more easily and with less injury from fixed and 

 partially decalcified than from fresh cochleae. 



It was early found that with cochleae whose bony labyrinth 

 was advanced, a greater percentage of normal appearances 

 could be obtained if a small hole was made through the bone at 

 the apex, before or within two hours after placing them in the 

 fixing fluid. In doing this, very great care had to be taken not 



