Acari in Photographic Baths and Chemical Solutions. 379 



porous red oxide of iron from Vesuvius, connected by platinum 

 wires with, a voltaic battery. On the fourteenth day lie noticed 

 a few whitish excrescences, or nipples, which proceeded to 

 develope filaments, and on the twenty-second day assumed 

 the forms of perfect acari. Mr. Crosse observed, when these 

 facts were commented on : u l never ventured an opinion 

 as to the cause of their birth, and for a very good reason — I 

 was unable to form one." He succeeded in obtaining similar 

 acari in solutions of nitrate, and sulphate of copper, sulphate 

 of iron, and sulphate of zinc ; likewise in solutions of silicate of 

 potash, and fiuosilicic acid. The latter experiment occupied 

 eight months, when the creatures appeared at the negative 

 pole. Mr. Weekes of Sandwich repeated these experiments 

 with silicate of potash " inverted over mercury, the greatest 

 possible care being taken to shut out extraneous matter, and 

 in some cases filling the receivers with oxygen gas." In these 

 instances the acari appeared after the lapse of more than a year. 

 Dr. Noad made similar trials, and after more than sixteen 

 months found the acari on and about the terminal cells of the 

 battery, but not within the bell -jars. Mr. Crosse repeated his 

 experiments, with greater precaution to exclude extraneous 

 matter, and with the same results ; but he discovered that it 

 was necessary, as mentioned by Mr. Slack in the discussion at 

 the Microscopical Society, to furnish the little animals with the 

 means of emerging from the fluid. He noticed that " if he let 

 an acarus fall into the fluid under which he was born, he was 

 immediately drowned," and Mr. Weekes observed the same 

 fact. In another case the acari were developed in an atmo- 

 sphere of chlorine, but they were motionless, and Mr. Crosse 

 remarked, "whether the chlorine prevented their complete 

 animation, I cannot say." 



The nutrition of creatures formed under such circumstances 

 is as difficult to account for as their origin j but the paper in a 

 former number of the Intellectual Observer on the Condi- 

 tions of Infusorial Life, will suggest many considerations that 

 may be advantageously borne in mind. In remarking upon 

 Dr. Maddox's experiments, Dr. Lankester suggested that the 

 paper with which his vessel was covered may have furnished 

 some nutritious matter for the singular visitants ; and he also 

 pointed out the great importance of studying manifestations of 

 life under unusual circumstances. 



No mention of the objects discovered by Crosse and Weekes 

 appears under the head Acarus in the Micrographic Dictionary . 

 A certain portion of the scientific world found their prejudices 

 interfered with ; so some misrepresented, and others suppressed 

 what had actually occurred. Dr. Maddox is fortunate in having 

 made his observations when better treatment may be anticipated. 



