THE FROG 



11. Cross-sections of the stomach.- -Using a freshly- 

 killed young frog with stomach in the resting condition, cut 

 out the entire stomach and fix twenty-four hours in Zenker's 

 fluid. After passing the object to 96 per cent, alchohol, trim 

 off the pyloric portion and the extreme cardiac end. Sec- 

 tions should be cut with a thickness not exceeding 8 /*. Stain 

 on the slide with Delafield's haematoxylin followed by orange 

 G or Congo red. 



12. Cross-sections of the kidney. Remove the kidney 

 from a fresh frog by cutting around the organ so as to in- 

 clude adjacent portions of the peritoneum and ureter; care 

 must be taken not to tear off the peritoneum from the ven- 

 tral surface of the kidney. Fix twelve to twenty-four hours 

 in Zenker's fluid. Discard the anterior third and the ex- 

 treme posterior end, and cut transverse sections &n thick. 

 Stain on the slide with Delafield's hsematoxylin followed by 

 Congo red. 



13. Thyroid glands. The hyoid apparatus with thyroid 

 glands attached should be prepared by staining the object 

 in toto with borax-carmine and mounting it in balsam on a 

 slide. In order to flatten the object on the slide, fasten the 

 cover glass with rubber bands while the balsam is hardening. 

 This preparation should be demonstrated while the students 

 are studying the respiratory system, in order that they may 

 avoid injuring the glands while dissecting out the hyoid 

 apparatus. 



Sections of the thyroid gland should be prepared as fol- 

 lows : Since the object is extremely small it should be cut 

 out with a piece of cartilage attached to aid in handling it; 

 but the bony thyrohyoid process must be removed. Fix 

 for a few hours in Zenker's fluid, cut sections about 8 ^ thick, 



