44 



was much pleased with it ; it could be used very well with a 4in. or even a 5in. 

 objective, and showed a very much larger field than that of the ordinary eye- 

 piece. He thought that if the diaphragm was removed from an A or B eye- 

 piece, it would be much more useful with low powers, and he commended the 

 practice of making the diaphragms moveable in such eyepieces to enable 

 them to be easily adapted to show a larger field when a low power object 

 glass was used. He could strongly recommend Mr. Moginie's new instrument 

 for the use of students and for botanical purposes. 



Mr. T. C. White read a paper " On the Aquarium as a field for microscopical 

 research," in which he minutely described the method of constructing, stocking, 

 and maintaining a marine aquarium in a London home. 



The President said that Mr. White had in his paper spoken of his laziness, 

 but he did not himself think that the paper was an evidence of it. The interest 

 attached to the subject was boundless, and he should be very glad to hear the 

 remark of any of the members upon it. Two or three minor points occurred to 

 him in connection with it— first, he believed that the habits of the creatures 

 kept in aquaria were, for thl most part, nocturnal, or at least that they 

 often preferred a subdued light ; even amongst fishes, he believed this 

 was largely the case, and yet he often went into rooms and saw great 

 tanks of clear glass without a particle of shade provided for the creatures 

 to take shelter in, and he could only call this gratuitous cruelty. Then all 

 these creatures were expected to live for an indefinite time without any 

 means being taken to aerate the water duly, no attempt being in 

 many cases made to supply it, and then people said " they don't know 

 how it is, but they can't get their fishes to live." The question of aeration 

 was one of great importance, and required study. A friend of his made it a 

 condition that everyone who went to look at his aquarium should give it three 

 charges of the water from a syringe, and another fixed a bellows to the door of 

 the room, by means of which a change of air was forced into the water whenever 

 the door was opened. With respect to the difference between natural and arti- 

 ficial sea water, he believed that iodides and bromides of magnesium and sodium 

 entered into the composition of sea water in its natural condition, and he should 

 like to ask Mr. White if lie found it necessary to supply them. 



Mr. T. C. White said that with regard to the iodides and bromides, their pro- 

 portion was so extremely small that he thought their absence made no difference. 

 Mr. Lloyd, of the Crystal Palace Aquarium, told him that they were not really 

 necessary, but they would in the course of time be developed, especially if sea- 

 weeds were washed in the water. The sea water in his own aquarium had been 

 unchanged for three years ; it was given to him in the first instance by Mr. 

 Lloyd and he believed it came from Brighton. During the last summer 

 Oscillatorice were developed in it in such numbers that the water became foul 

 and many of the creatures, including the Serpulce, died. He exposed it how- 

 ever, to strong sunlight, and this caused oxygen to be given off in such large 

 quantities that the water became quite purified, and it was now quite " lookino- 

 up" again. • It was an excellent plan to occasionally wash fresh seaweed in the 

 water, as this supplied quantities of germs and other matters which were 

 beneficial. He quite agreed with the President as to some people's ideas re- 

 garding an aquarium. Some of his patients having seen his aquarium went 

 away delighted, and forthwith set up one for themselves ; they went to Brighton 

 or Weymouth and brought home things to put into it, but very soon after there 

 was no more heard of it, and they would say, "Oh, it was no good keeping it, 



