1894.] MICROSCOPICAL JOURNAL 303 



METHOD. 



The method I have followed in making my observa- 

 tions is simple in the extreme. First, I constructed a 

 platform for the stage of my microscope, on which to 

 place the frog, consisting of the parts to be mentioned. 



I took a piece of cork, twelve inches long, four inches 

 in width, and half an inch in thickness at the center of 

 its long diameter and an inch from its side I cut a hole 

 two inches long and about an inch wide ; over this I placed 

 a glass slide, such as is used in microscopy, sinking its 

 two ends even with the surface of the cork. The slide 

 entirely covers the hole cut in the cork. 



A quarter of an inch from the outer edge of the slide, 

 I cut a groove in the cork running a little beyond the 

 ends of the slide and parallel with it, and a quarter inch 

 from each end of this groove, another groove at right an- 

 gles to it, which is connected with the rubber pipe to al- 

 low for drainage, if needed. The groove is intended to 

 contain the intestine. 



This apparatus is simply fastened upon the microscope 

 stage, seeing that the glass slide covers the aperture in 

 the stage, and the frog arranged upon it, after being cu- 

 rarized by injecting a little of a watery solution of the 

 poison in the dorsal lymph sac. 



If the web of the foot is to be examined it is simply 

 stretched across the slide and held in place by felted 

 pins, placed between the toes but not piercing them. 



If the mesentery is to be examined, the frog is placed 

 on the apparatus after being curarized, the abdomen 

 carefully opened and the intestine gently lifted out with 

 felted forceps and placed in the groove, thus stretching 

 the mesentery smoothly over the slide where it can be 

 easily examined. My method was to get a fresh frog 

 from a pond near by each time I needed one. 



On the first ten frogs I made no observations whatever 

 of the mesenteries but only of the foot webs, while on the 



