HIJKSIOKNT S AOnRKSS. XI 



should scarcely deem it woitliv of mention, only that evidence 

 is plentiful that it is often entirely overlooked even by tliose 

 who are presumed to be fairly expert. 



I have often felt amused — and the source of amusement is 

 still open to us — at the many fanciful things which have been 

 said about that delightful object for the microscope, Volrox 

 illnhiitor. How is it, it is asked, that it is found in abundance 

 one day and has entirely disappeared the next ; and what 

 becomes of it in winter "? Does it assume some strange garb 

 and pass unrecognised and unrecognisable in its disguise, or is 

 its existence left to the so-called winter spores seen in the 

 Volrox nnrem of Ehrenberg, which are supposed to sink in the 

 mud only to appear again with the coming sunshnie ? 



Now I made Yolvox my special exhibit so many winters 

 at our Midland Institute Soirees that I became fairly ashamed 

 to show it ; and as it is a most difficult thing to keep in artificial 

 aquaria for any considerable time, I had often to renew my 

 stock from some natural source, which I was nearly always 

 able to do, in summer or winter. 



Whence, then, come all these mysteries about its appear- 

 ance to-day and its disappearance to-morrow ? Why, the fact 

 is, many who seai'ch ponds for this and other free organisms 

 do not take the necessary means to find out whether it is 

 present or not, and unless a few dips suffice to secui'e specimens 

 it is at once settled that the thing is not there. 



The explanation is that Volvox is greatly stimulated by 

 light and warmth, as is usually the case with plant life, and 

 under these favourable influences it will not only increase at a 

 great speed, but will roll through the water in every direction, so 

 that the most hap-hazard dip witlj a bottle is sure to secure 

 specimens ; and I have many times seen it even covering the 

 banks like a green sciun where the water has receded and left 

 it stranded, as we see marine objects on the sea-shore. 



But in winter or times of extreme cold it makes its 

 retreat from the " weather "' side of the water, and is to be 

 sought very near the bottom in some shallow part where the 



