32 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



still. It is possible that the ones which died might have done so any 

 way as the others did in the running water, and I should think, judging 

 from those put in the cold chest that lobsters might be kept alive for ;i 

 number of days in a temperature of from 40° to 45° or 50°. I think 

 34° was a little too cold for them. At present I could not well regulate 

 the temperature, but hope at some future day to give it another trial. 



I placed several lobsters in water at the freezing point. They were 

 just alive after one hour's immersion, but did not recover when placed 

 in running water. All these lobsters were taken from water at a tem- 

 perature of C9° and 70°. 



Washington, D. C, October 21, 1884. 



6 — DIBECTSOWSFOB COLLECTING EMBIOTOl OID B'BSEI EMBRYOS. 



By JOHN A. B¥DEB. 



The species collected should be carefully identified, if the adults are 

 not sent along with the embryonic material. Locality, etc., are also 

 essential, together with dates of collecting. 



If the gravid ovaries are removed it should be very carefully done, 

 so as not to bruise, crush, or displace the contents. The gravid ovaries 

 should then be placed in from ten to twenty times their own bulk of 

 Midler's fluid, where they can remain for three or four weeks, but 

 should not be so crowded into the phials as to be malformed. On the 

 whole it would be preferable to get as small a species as possible and 

 preserve the gravid adults entire in Midler's fluid, the body-cavity being 

 first opened carefully to allow the fluid access to the interior. In this 

 they may remain three or four weeks before removal into two or three 

 changes of water during a day, when they may be put into 70 per cent, 

 alcohol. Washing or soaking in water is desirable for a day to get rid 

 of the salts in the fishes which discolor the alcohol and also, in combina- 

 tion with the latter, make the objects brittle. 



It is very desirable that the embryos be in their normal positions and 

 relations to the adult in the ovaries, and that as many stages as possi- 

 ble be obtained in order that my studies may be as consecutive as pos- 

 sible. 



The Midler's fluid will be supplied in packages of If, 13, 13, or what 

 is enough of the powdered potash-bichromate, and sodic sulphate to 

 make a quart of fluid with that amount of clean, fresh water. The 

 material collected should be addressed to John A. Ryder, Smithsonian 

 Institution, Washington, D. C. 



Glass jars will be the best to keep the material in. Fruit jars with 

 screw tops answer the purpose well and prevent the leakage of the yel- 

 low Midler's fluid. 



