PEOCEEDINGS OF THE SOCIETY. 479 



Mr. Crisp called attention to another novelty, which for obvious 

 reasons was not exhibited that evening, viz. a type slide of diatoms 

 by J. D. Moller, containing 1600 species, the price of which was 

 1600 marks, or SOI. MoUer's type slides, he might add, were now to 

 be had mounted in four different media, including phosphorus and 

 monobromide of naphthaline. 



Dr. Braidwood read his paper " On Observations on Three Human 

 Contagia," the subject being illustrated by specimens exhibited under 

 the Microscope. 



The Chairman expressed the pleasure with which he had listened 

 to this very interesting paper upon a subject of so much importance, 

 the area of which seemed widening every day. 



Dr. Maddox said it would, in connection with this subject, be 

 interesting to know that the Aeroscope, which he had the pleasure 

 of exhibiting at the last meeting of the Society, was an instru- 

 ment specially designed for carrying out observations such as those 

 described in the paper. There could be no doubt that the sub- 

 ject covered a very wide area, so great indeed as to be beyond the 

 compass of any private individuals, so that the subject was one which, 

 owing to its great importance, he thought should be worked out with 

 the assistance of the Government. This was how it was being 

 investigated in Paris, with very remarkable results. He held in his 

 hand, and would submit for examination, a most interesting diagram, 

 which had been prepared from the consideration of some 80,000 ex- 

 periments at Paris, and which showed that the atmosphere, though 

 laden with these germs, was not homogeneously so. There were 

 many more at some periods than at others, and it was found that 

 rainfall diminished the number very considerably. They needed, 

 however, all the information it was possible to obtain, and a large 

 amount of careful observation would be necessary before they could 

 arrive at any definite conclusions. At present they were imable to 

 say that the death-rate was sensibly affected by the quantity 

 found. 



Dr. Anthony inquired if there was any great difficulty in staining 

 the specimens with Vesuvian brown ? All that really appeared to be 

 necessary was to stain with something which would affect the germs 

 more than the surrounding medium. As described in the paper, it 

 would seem to be a very simple thing to repeat the experiments and 

 to verify them. He might mention, as a practical point to be noted, 

 that all these zymotic diseases became much more infectious towards 

 the conclusion of their course, and that they were far more so after 

 the patient was up and apparently recovered than when he was down 

 and lying in bed, and that it was when the disease was passing away 

 that it was really the most contagious. 



Dr. Braidwood, in reply, said that, with regard to the staining, the 

 process was quite simple, and was arranged so as to involve as little 

 manipulation as possible. The drop of albumen was dried gently 

 over the spirit-lamp with great care, and the slide was then laid with 



