of the Poly gastric Infusoria. 437 



he quotes. Even if ciliated organs do really occur in the spores 

 of Algae, these cannot be regarded as true locomotive organs. 

 Their peculiar motions, with which natural philosophers are at 

 present so much occupied, also occur without locomotive organs, 

 and take place in other substances, as small particles of dust. It 

 appears to be proved by Ehrenberg's observations on the spores 

 of Saprolechnia (Conferva ferax, Gruith ; Achlya, N. ab Esenb.), 

 which I can confirm, that chemical processes are the chief agents 

 in it. This view finds support in the following discovery : I oc- 

 cupied myself for some time during the past summer with in- 

 vestigations on the process of germination in our Cerealia. The 

 minute particles which occur in the cells of the grains among 

 the large granules of starch, at first did not exhibit the least trace 

 of motion ; but as soon as germination began they moved actively, 

 and when the first leaf sprouted out, the movements were so 

 remarkable, that I could hardly distinguish them from those of 

 the ripe spores of Achlya prolifera. Siebold's opinion, that in 

 many of the organisms figured by Thuret we might recognise 

 several which Ehrenberg has described as Monadina and Volvo- 

 cina, is quite correct. But which of the two is in error ? Is it 

 Ehrenberg's fault, if Thuret figures Infusoria as spores of Algse ? 

 I shall hereafter enter upon Thuret's memoir in a separate com- 

 munication and point out the errors contained in it-. 



3) " Many of these lower vegetable formations (Bacillaria and 

 Diatomeai) have been considered as animals from their locomotion, 

 although the alterations in position observable in them do not 

 give the slightest impression of their emanating from 'an internal 

 will of the organism. " It is at once obvious, that the actual 

 impression which these minute creatures make upon the observer 

 cannot afford grounds for deciding any question, for in matters 

 of science we require objective grounds. I must also confess, 

 that when / first observed these animals, they gave me the im- 

 pression of this alone. Hence we have both observed one and the 

 same thing and derived different impressions from it. 



Covering of the Body. 



3. The Poly gastric Infusoria are either furnished with a cara- 

 pace or not. When present, it either consists of silica, which in 

 many cases contains a considerable per-centage of oxide of iron, 

 or it is more of a horny nature (Closterina) . The carapaces assume 

 various forms ; being sometimes oval and truncated at the ex- 

 tremities, sometimes very narrow and pointed at the extremities, 

 sometimes broad and symmetrically excavated at the sides, and 

 many other varieties of form. Among those not having a carapace, 

 there are some which are inclosed in great number in mucoid 

 masses, as the Ophrydina, which live together frequently by hun- 



