PKOCEEDINGS OF THE SOCIETY. 979 



were so slightly ruled that their practical value was very small. The 

 lines ruled by Nobert were very much more distinct, and, therefore, 

 much better as scales. 



Mr. Crisp said that with regard to the claim to have ruled 

 1,000,000 lines to the inch, the only suggestion of a proof was that 

 the micrometer screw had been set to that degree of fineness, which, 

 of course, was quite another matter (see p. 949). 



Mr. Dreyfus called attention to slides of Syzygites megalocarpus 

 by Dr. Zimmermann, Professor of Botany at Chemnitz, who had 

 acquired considerable reputation for mounting micro-fungi. These 

 slides showed distinctly both zygospores and azygospores, proving 

 that this spore is also formed without conjugation. He also ex- 

 hibited slides of Aspergillus glaucus, Pilobolus crysialUnus, and Mucor 

 racemosus. 



Mr. Crisp said they had to regret the deaths of two gentlemen 

 well known in the microscopical world. Mr. C. S. Nachet, the founder 

 of the French firm of that name, had died on the 28th October at the 

 advanced age of 83, and Mr. C. A. Spencer, of Geneva, U.S.A. (one of 

 the early makers of objectives with apertures exceeding that of 180^ 

 dry objectives), had died on the 28th September. 



The Rev. Dr. L. G. Mills' paper on " Diatoms from Peruvian 

 Guano" was read, and was illustrated by specimens exhibited under 

 the Microscope and also by drawings (see p. 865). 



The Chairman said he did not notice that the author had suggested 

 any reason for the changes which he had observed to take place in 

 the species of diatoms now found in this guano. 



Mr. Michael said that the teim " Peruvian Guano " was a very 

 wide one, and he thought that as the first deposits of this substance 

 were pretty well worked out, what came over here now was from 

 another deposit altogether. He, therefore, inclined to think that this 

 change in the varieties of the diatoms really indicated that the 

 deposits now received were from a new locality, or it might even be 

 that the old deposit was being worked at a much lower level than 

 formerly. Moreover, although various guanos may correctly be 

 called "Peruvian," still they might come fi'om widely different 

 districts. 



Mr. Casaux said that his experience was that there were no two 

 cargoes of guano alike, but that it came from various places, and its 

 uniformity of quality coidd never be depended upon. 



Mr. T. Charters White said he had for many years past felt the 

 need of some apparatus by which the development of the lower forms 

 of animal life could be watched under the Microscope under similar 

 conditions to those in which the objects naturally existed. A larcre 

 number of growing slides had been brought before them, but he had 

 never found that they were of very much use, certainly not so useful 

 as one which was given to him a short time ago by a member of the 

 Quekett Club, Mr. W. Goodwin. It was necessary in any contrivance 

 of this kind to have the objects kept constantly wet, and to afford an 

 opportunity of constantly observing them without the danger of their 



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