148 



THE PLANT-LIKE INFUSORIA. 



Fig. 89. 



separates the two parts of the mi- 

 nutely sculptured shell (2, t 1 ). It 

 is in this animal that, as we ascend 

 from the lower to the higher kinds 

 of Infusoria, we find for the first 

 time a disposition of the cilia which 

 prevails so generally among the 

 aristocrats of their class. I need 

 but to remind you of the Stentor, 

 which I described when speaking 

 of the self-division of Infusoria 

 (p. 62, and fig. 30) and other an- 

 imals. The habits of the Cerati- 

 urn, whilst swimming, correspond 

 to the arrangement of these cilia : 

 it progresses with a spinning mo- 

 tion, boring its way through the 

 fluid by being whirled, like a wheel on its axis, by means of the 

 transverse vibrating motion of the belt of cilia, whilst its double 

 proboscis (/, Z 1 ) plays the part of a tactile organ. 



I will detain you here with but one more example of the pro- 

 gressive series, simply that the investigation shall have fairly 

 entered the bounds which include the true, so-called ciliated Infu- 

 soria. You would hardly suspect at first glance that this oval 



figure here (fig. 90) possessed any 

 configurative relationship to the 

 trumpet-shaped Stentor (fig. 30) ; 

 but yet, the young (fig. 91) of the 

 latter, when placed beside this, 

 Plcuronema, cannot fail to strike 

 you with its resemblance to it 

 (compare figs. 90 and 91). I hope 

 hereafter to prove to you conclu- 

 sively that the similarity is based 

 upon an idea of form which is 

 common to both of them, and, in 

 Fig. 90. fact, to all Protozoa. 



