4o6 



E. WACE CARLIER 



From the first snap to thc disappearancc of thc worm finally within the 

 mouth a period varying from five to ten minutes elapsed and was carefully 

 noted in each case. Time being counted subsequently from the moment of 

 disappearance of the worm. 



Of thèse newts one was killed every half hour for the first few hours, 

 and subsequently at intervais of an hour. In this way as far as was possible 

 every varient except time was eliminated, though not with complète success, 

 for in a few cases it was afterwards found that some parasitic disease of the 

 mucous membrane of the stomach was présent and those so affected were 

 removed from the séries. 



Thèse constituted the second set of experiments. 



METHOD OF PREPARATION. 



At the prescribed time each newt was pithed, opened, its stomach, 

 duodénum and gullet removed without injury and placed upon a pièce 

 ofthinpaper. Thèse viscera were then opened by a longitudinal incision 

 through their entire length ; their contents, if any, removed and the organs 

 spread out flat upon the paper without stretching, their mucous surface 

 uppermost. They were then immersed, paper and ail in Mann's " picro- 

 corrosive fixing solution (modified formula, sp. gr. 1020), in which they 

 remained till next day, when saturated corrosive sublimate (M. Heiden- 

 hain's '" formula) was substituted for it. At the end of another twenty 

 four hours this was removed and the tissues taken up the alcohol séries 

 into chloroform and finally embedded in paraffin (58° G.) (1). Longitudi- 

 nal sections were then eut in séries with the Cambridge rocking microtome 

 set to four teeth and fixed upon albumin coated slides after spreading on 



warm water. 



To insure equality in staining and therefore comparability sections 

 from one newt were used as a test objects and ail the slides stained up to 

 them. The most efficient way of doing this is to place one section of the 

 test newt upon each slide and to see that in ail cases that particular section 

 is stained to exactly the same tint. This test section may be placed at one 

 end of the slide and subsequently wiped off if desired before the other 

 sections are finally covered. 



c 



(I) I am in the habit of using this hard paraffin oi' cven a 60° paraffin as I iind I can 

 ut the fmest possible sections with it (one tooth of the rocker). 



