PROCEEDINGS OF THE MICROSCOPICAL SOCIETY OF LONDON. 79 



it in water ; this separates the albumen, while the uric acid is deposi- 

 ted, presenting, not a crystalline form, but a soft powder, like that of 

 Lycopodium. The granules of this powder present, under the micro- 

 scope, a spherical, transparent, and variable size, the largest measuring 

 0.00014", the smallest 0.00006", and the mean 0.00010" of an inch. 

 A grain and three quarter of uric acid may be obtained from a common 

 snail. 



Mylius has met with this acid in Helix nemoralis and H. hortensis, 

 but has never been able to meet with it in the genera Lymneus and Pla- 

 norbis. |The acid is neither combined with ammonia or any other alkali, 

 but is secreted in a state of purity by the secreting organ. January, 

 1841. 



PROCEEDINGS OF THE MICROSCOPICAL SOCIETY OF LONDON. 



May 27th, 1841. Professor Owen, F.R.S., SfC. President, in the Chair. 



After the preliminary business of the meeting, the Secretary proceeded 

 to read a paper from Dr. Haro of Metz, being " Observations on the 

 production of Infusoria ;" but as the author did not appear to be aware 

 of what had previously been done by other philosophers connected with 

 the history of the subject, we content ourselves with giving only the con- 

 clusions arrived at by the author, viz. 1. That the air is not in all cases 

 the vehicle of the germs of true animalcules. 2. That substances in a 

 state of putrefaction, only contain animalcules when in contact with 

 other substances in which they already exist, and that they are not 

 developed, except under certain circumstances. 3. That decomposition 

 of organic matter only gives birth to rudimentary species, Vibriones and 

 Monades, which, generally speaking, are not animals ; and that if true 

 animalcules can be observed in them, these can only be regarded as 

 larvae deposited in their substance by minute insects flying in the air, 

 such as occur in the vibrios of paste and vinegar ; that, consequently, 

 there is not here any spontaneous generation, properly so called. 

 Finally, that all other particles are rudimentary crystalline atoms, which 

 are detached from organized bodies under decomposition, and are put in 

 motion by electrical forces, until the aggregation of the molecules con- 

 stitutes them solid bodies, under the form of the crystals which the 

 substance affects to which they belong. 



The most important fact detailed by Dr. Haro was, as Dr. Arthur 

 Farre observed, the test for discovering the presence of albumen and 

 fibrin, should it prove on repetition to be correct. Dr. H. states, that 

 when albumen is subjected to decomposition in water Monades are pro- 

 duced ; and, on the contrary, when fibrin is so treated, Vibriones are the 

 animalcules met with in the fluid. 



Professor Owen also made some remarks on the communication, in 

 which he stated that the author could not have been acquainted with 

 the previous researches of Professors Ehrenberg, Schultz, &c., and that 



