STAINING TAIL FIN CHROMOSOMES 



27 



2. Dehydration: This may he accomplished rapidly through the alcohols, 

 vdth 5-iiilnute changes in each grade, or through three 15-iiilnute 

 changes in dioxan. 



3. Clear in xylol and mount in clarite. 



Such large pieces of epidermis may he difficult to handle. If time permits, such 

 pieces can be fastened to slides with thin celloidin and then stained. If permanent 

 mounts are not required, chromosome counts can he made within k hours after fixation hy 

 reducing the hydration time. 



Tr im off outermost 

 edge of tail fin 

 with sharp scalpel 



(The tail fin is tr Median ventral 

 be peeled back froff cut 



this cut edpe of 

 body sl<in.) 



Oistal end of tail fin may 



c 



v 



CHROMOSOMES IN TAIL TIP OF A. PUNCTATUM 



THE METHOD OF HENLEY-COSTELLO (for Urodela) 



The following method is excellent for Triturus, fair for Amblystoma, and poor for 

 Eana and other Anura. In any case, the tail tip which has regenerated for 12-1'+ days 

 after amputation Is better than the original tall tip since it will be freer of pigment. 

 One can generally count on from 5^ to 55^ of the cells showing mitotic figures, if the tail 

 tip is taken from animals in which the yolk resorption is complete and feeding has begun. 

 The (unpublished) procedure is as follows: 



