360 THE AMERICAN MONTHLY [Nov. 



Ascidians. — Molgula and Cynthia were readily killed with 

 siphons open after ansesthetisation with magnesium sulphate. 

 In this case -it is best to add the saturated solution of sulphate 

 intermittently with a pipette. 



Ctenophores. — After considerable experimentation, a method 

 for preserving these delicate creatures in a nearh^ life-like ap- 

 pearance was devised. Formalin alone in solutions of varying 

 strength had been tried without success. It was found neces- 

 sary to treat the animals with some hardening reagent before 

 placing them in the formalin, and the following method seems 

 to be the most successful : — To a solution of equal parts of 2 per 

 cent formalin and Perenyi's fluid was added enough common 

 salt (NaCl) to increase the density of the mixture to that of 

 sea-water — i. e., until a Ctenophore placed in it barely floated- 

 This adjustment of the density of the surrounding medium 

 prevented the Ctenophores from collapsing of their own weight. 

 After remaining for about half-an-hour in this fluid the}' were 

 transferred to 4 per cent formalin, the d-^nsity of which had 

 been increased by the addition of either Epsom salts or com- 

 mon salt, so that the Ctenophores again barely floated. Epsom 

 salts is probably better than common salt for increasing the 

 density of the fluid. Some specimens which were preserved in 

 formalin x NaCl began to shrink after a few days ; while some 

 (Mnemiopsis) which have been preserved for nearly six months 

 in formalin x MgSOi are still in excellent condition. 



After the Ctenophores have been properly preserved, precau- 

 tion must be taken in transporting them, for they are easily 

 torn to pieces. If they are placed in bottles filled with fluid of 

 the proper density and the cork so inserted as to leave no air- 

 bubbles, this danger is reduced to a minimum." — American 

 Nataralist. 



Microscopy on a Railroad Train in Motion. — Going to 

 Portland in August, 1895, I wanted to show a gentleman a Gor- 

 dius hair worm (hair snake); vulgarly sup])osed to be born from 

 horse-hairs soaked in water. With a one inch objective and a 

 1 inch ocular there was no difficulty in demonstrating the tu- 

 bular head, the brown dark outlined body and the forked tail 

 by means of my clinical microscope. The tube stage and eye 

 all shook and moved together. I have used the clinical micro- 



