252 HETEKOGENBTIC OEIGIN 



him ' Wasserbaren ' or Water-bears ; while later on they were 

 termed 'Sloths' by Spallanzani, who devoted much attention to 

 their tenacity of life and power of recovery after long periods of 

 dessication in tufts of moss and lichen. 



The specimens that I have had under observation have been 

 found in association with the great Amoebas referred to in the 

 last section, together with certain Rotifers, obtained from portions 

 of a yellow lichen {Parmelia parietina) brought from Bagnieres de 

 Luchon seven months previously, after they had been soaked in 

 distilled water from seven to ten days. The fragments of lichen 

 were allowed to soak for this long period (the weather being cold) 

 because in this way, as I have previously indicated, many more of 

 the specimens of Amoebae, Rotifers and ' Sloths ' dropped away 

 from the lichen and were obtainable than would have been the 

 case if the soaking had only been for the few hours needful to 

 enable these and other organisms existing in the lichen to resume 

 their active life. 



A drop of the fluid, left after this soaking, together with some of 

 the sediment, was transferred by a tiny pipette to a microscope 

 slip, and on each side was placed a minute fragment of one of the 

 thinnest cover-glasses, so as to protect the organisms from pressure 

 and allow them to move about after a cover-glass has been applied. 

 Every portion of this drop was then thoroughly scrutinised under 

 the microscope, with the result that occasionally one, two, or even 

 three specimens of Macrobiotus would be found — young or old, 

 living or dead. 



They are of a I'ed-brown colour, owing to the presence of much 

 pigment of that tint in different parts of the body, but especially 

 in a broad band of pigment cells lining the inner side of the in- 

 tegument along the middle and lateral regions of the back. This 

 superabundance of pigment is one of the distinguishing features of 

 M. Oberhduser. It is more plentiful in some individuals than in 

 others, and especially in old specimens. Many of them contained 

 great dark-coloured eggs, varying from two to five in number, such 

 as are shown in Figs. 55, A, 56, A. 



My attention was specially directed to these creatures owing to 

 the following circumstance. I was at the time studying the de- 

 velopment of Ciliates from the eggs of Callidinse, as described 

 elsewhere.' I placed, on March 18, 1902, a shp containing 



■ "Studies in Heterogenesis," pp. 119-124, PI. IX., figs. 95-98. The Ciliates 

 produced from these Rotifers belonged to the genus Glaucoma. 



