Alcide cVOrhigny. 39 



He points out that the chambers of the shells are iilled with a 

 very contractile rose or orange-coloured animal-matter of the 

 consistency of thick mucus, capable of extension in threads, and 

 filled with irregular granulations. From the interior of Miliola 

 he had seen protruded a soft mass analogous to the interior 

 substance, which changed its form slowly under the Microscope.^ 

 He had made some observations on Miliolina, Cristellaria, and 

 Vertebralina living on algte at a depth of one metx^e. He observed 

 that when a washing of these animals was placed in a glass 

 vessel one sees them after a few hours attached to all its sides, 

 independently of the direction of light, from which he concluded 

 that they are not heliotropic.'-^ He observed the pseudopodia 

 spread out and radiating from each " centre of adherence," and 

 that, measuring '01 at their bases, thev extended to a distance 

 five times the diameter of the shell, becoming of extreme tenuity. 

 By means of these pseudopodia the animal crawled at a rate of 

 about 5-7 mm. in an hour. He made the further highly interesting 

 observation that in time the animals crawl up to the surface level 

 of the water and " continue to crawl along its surface hanging 

 below it like certain gasteropod mollusca." This observation was 

 made by myself' in my tanks at Selsey in the year 1915, and does 

 not appear to have been made by any other zoologist between 

 1835 and that date. 



Dujardin pointed out, quite accurately, that Polystomella 

 crawls more slowly than Miliolina, and that the form to which 

 he had given the name Gromia oviformis was slower still. His 

 account of the formation of the pseudopodia and the use made 

 of them in crawling {reptation) is complete, and since liis day 

 nothing has been added to our knowledge of this phenomenon. 

 "One cannot see in this,'' he says, "veritable tentacles; it is a 

 primary animal substance which extends itself and grows some- 

 what after the manner of roots ; the extreme slowness of the 

 movement alone is sufficient to prove this." He then notes the 

 fundamental difference in the manner of the extrusion of the 

 pseudopodia in perforate and imperforate genera. He concludes, 

 again, that they must be classed among the lowest forms of life, 

 and regard being had to the above observations he abandons the 

 term " Symplectomeres " and proposes the name by which the 

 group has since been known, " Ehizopoda." ^ 



In a third note, published in November of the same year (1835) 



' It will be observed that this is a new observation. He had previously said 

 that no part of the body was extruded excepting for the formation of new 

 chambers. 



- This is not entirely accurate ; a certain measure of heliotropism has been 

 established by later observations. 



^ This paper attracted a good deal of attention on its publication. See notices 

 in Le Temps (June 24) and I'Echo du Monde Savant (June 26). 



