CHROMOSOMES OF INDIAN RUNNER DUCK. 333 



100 per cent, alcohol plus half xylol, 15 minutes; pure xylol, five 

 minutes; one half xylol and one half 48 paraffin, fifteen minutes; 

 then embedded in the usual way. They were cut at seven micra 

 and stained with Heidenhain's hematoxylin and the work com- 

 pleted as is usual for such material. These slides were used in 

 determining the sex of embryos whose membranes had furnished 

 cells for study. 



Technique for the Sectioned Material of the Testes. The testes 

 were from eight-months-old individuals. On removal from the 

 body they were cut into millimeter cubes and dropped into the 

 same fixative as above as soon as possible. They remained in the 

 fixative two hours at 37 then were washed in several changes of 

 distilled water at the same temperature. The material was now 

 passed through the following grades of alcohol, two minutes each: 

 |, i, 2, 3, 4, 5, 6, 7, 8, 9, 10, n, 12, 15, 18, 20, 22, 25, 30, 35 

 and 40 per cent. At this stage all the alcohol was drained off 

 except enough to cover the tissues. Then by means of a pipette, 

 equal parts of bergamot oil and 50 per cent, alcohol were dropped 

 in. The mixture was stirred constantly by bubbling it with a 

 pipette. Again all the liquid was drained off except just enough 

 to cover the tissues, and in each of the following changes this rule 

 was observed. Equal parts of 60 per cent, alcohol and bergamot 

 oil; equal parts of 70 per cent, alcohol and bergamot oil; pure 

 bergamot oil. The old oil was now drained off and fresh bergamot 

 oil dropped in. This process was repeated several times until 

 all the alcohol was removed. The tissues were then left in 

 the pure bergamot oil two hours (the tissues may be left in this 

 oil lor several hours without injury). The oil was then drained 

 off and three fourths parts of bergamot oil and one fourth part of 

 oil of wintergreen were dropped in, then one half bergamot and 

 one half wintergreen, one fourth bergamot and three fourths 

 wintergreen, pure wintergreen. Then the old wintergreen was 

 drained off and fresh added several times until no bergamot re- 

 mained. 



From the oil of wintergreen the tissues were carried by steps 

 through to paraffin. Sixteen bottles were used, starting with one 

 part paraffin and fifteen parts wintergreen and finally ending in 

 pure paraffin. Then the tissues were passed through several 



