20$ Thp: Zoologist — June, 1866. 



the whole universe. Certain powers, forces, or what you will, being 

 once set in action according to immutable sequence, all the phenomena 

 of creation follow in due time : nothing more is wanted. No doubt 

 people prefer the old notion, which gives us more importance. 



Henry Birchall. 



A short Description of an Acarus and Us Agamic Reproduction.* 



By Richard Beck. 



(Reprinled from the ' Quaitevly Journal of Microscopical Science' for April, 1866.)f 



After keeping one or two species of Acarus for a very considerable 

 time, and having no difficulty in increasing or diminishing their 

 number according to the treatment 1 pursued, it was much to m}' 

 surprise when about the middle of last summer they began rapidly to 

 disappear, and in a comparatively short time I was quite unable 

 to obtain from the whole of my stocks any living specimens. 



On one occasion, when making a general search to see whether the 

 Acari had merely moved their quarters, 1 found in the thread of a 

 spider's old cocoon a species of Acarus, so entirely different from those 

 I was looking for, and preswiting to me such novelty in appearance, 

 that I lost no lime in carefullj' securing this and one other specimen, 

 which were all I could find: one of these, however, was injured in its 

 capture, and died immediately. 



The general appearance of the one still left was that of a female, but 

 without a male I thought there would be no chance of obtaining any 

 reproduction of its species, and I had moreover no clue to the food it 

 required. Instead, however, of following the often too hastily adopted 

 plan of merely making a moimted preparation of my specimen, 

 I determined to preserve its life as long as possible, and I am now not 



* Since reading ibis paper Mr. Bockelt has shown me a specimen of the same 

 Acarus, mounted by J. Bourgoine, of Paris, which be names "Cheyletus dcs pilleteries 

 (rare)." 



f [I have thought it desirable to reproduce this important paper in a Zoological 

 Magazine, because iis interest is general, and extends beyond the limited circle of 

 inicroscopisls. Agamogenosis, in all [irobability, exists in nature to a far greater 

 extent than has yet been supposed. The observation by Professor Huxley, quoted by 

 Mr. Beck from the Linncan 'Traiisiiclions,' shows how great is the necessity to avoid 

 drawing any conclusions from the absence of evidence. The production of evidence 

 leads to positive inferences, but its absence is only valuable as illustrating the paucity 

 of observers on the insufficiency of their observations. — Edward Ncwman.l 



