Developmental History of Infusorial, Animal Life. 365 



about three weeks he invariably obtained forms of ciliated in- 

 fusoria. " The fusiform body of the circo-monas bears a long 

 whip-like cihum at its anterior end, and a short seta at its 

 caudal extremity : this finally drops off, and when exposed to 

 undue heat and light, the animal is transformed into an Amo3ba. ,} 



Mr. Samuelson^s results do not very materially differ from 

 my own, save in one or two particulars. I have not seen the 

 succession of generations take quite the same course, and the 

 animal and vegetable bodies generally appear simultaneously, 

 or so soon after each other, that it is at times difficult to decide 

 the priority of appearance ; but as my experiments have been 

 chiefly confined to collections of rain and distilled water, 

 ivithout the addition of vegetable matter of any kind, this will 

 materially affect the results. We are, however, quite agreed 

 as to the wide and general distribution and great tenacity of 

 life presented by these infusorial germs, With regard to the 

 supposed purity of rain-water, at no time can it be taken 

 without the numerous matters floating in the air being brought 

 down with it, and, consequently, within a few hours after it is 

 caught, Protococus pluvialis, Amoebce, and Circomonas, may 

 always be found in great numbers. It is somewhat remark- 

 able that the purest snow water, caught in a clear glass vessel, 

 and allowed to remain well corked, will, in the course of two 

 or three weeks, be found to contain Amoebce and Circomonas, 

 but it rarely presents other forms of animal life ; the vegetable 

 matter completes its growth very slowly, gradually passes 

 to confervas, and for a time no other change is seen to take place ; 

 so that it is painfully apparent that the atmosphere in which 

 we live and move and have our being is something more than a 

 mixture of gases, as apparently determined by chemical analysis. 



Mr. Grlashier's " blue mist/' which he believes to be in 

 some way associated with our cholera visitations, certainly 

 does not depend upon the presence of any unusually large 

 number of spores floating about in the air. Although 

 spores, etc., exist, as I have shown, in the atmosphere, in 

 greater abundance about the period of such visitations, they 

 also exist when the public health is good. And therefore it 

 should be regarded as a mere coincidence, if certain bodies prove 

 to be more abundant during the prevalence of epidemic disease. 

 But this " fungus-spore" theory is no new thing, for it is upon 

 record that rusts and mildews have sprung up so rapidly upon 

 articles of food and clothing, as to have appeared to herald 

 approaching plagues. A so called <c blood-rain" is said to have 

 been the forerunner of the plague of Eome. It has been 

 noticed, however, that the present year (1866) has been 

 especially characterized by the prevalence of all kinds of moulds 

 and mildews upon vegetation generally; we consequently 



