REPRODUCTION OF INFUSORIA 



785 



distinct generic form, Meyatricha. And, according to the observa- 

 tions of Mr. Badcock, 1 these Megatricha-fonna multiply freely by 

 self-division. After a short time, however, they settle down upon 

 filamentous Algae or other supports, lose their cilia, put forth suctorial 

 tentacles (which seem to shoot out suddenly in the first instance 

 but are afterwards slowly retracted and protruded with a kind of 

 .spiral movement), and assume a variety of anioebiform shapes (fig. 

 599, 1, 2, 3), some of them corresponding to that of the genus 

 Trichophrya. In this stage they, become quiescent at the approach 

 of winter, the suctorial tentacles and the contractile vesicles dis- 

 appearing; they do not, however, seem to acquire any special 

 envelope, remaining as clear, motionless, protoplasmic particles. 

 But with the return of warmth their development recommences, a 



FIG. 599. Immature forms of Podoplirya quadripartita : 1, Amoe- 

 boid state (Trichophrya of Claparede and Lachmann) ; 2, the 

 same more advanced ; 3, incipient division into lobes. 



footstalk is formed, and they gradually assume the characteristic 

 form of Podopkrya qaadrlpartita. A regular ' conjugation ' has been 

 observed in this type, the body of one individual bending down so 

 as to apply its free surface to the corresponding part of another, 

 with which it becomes fused (fig. 598, l) ; but whether this always 

 precedes the production of internal embryos, or is any way prepara- 

 tory to propagation, has not yet been ascertained. 2 



1 Journ. of Roy. Microsc. Soc. vol. iii. 1880, p. 563. 



- The Acinetina were described both by Ehrenberg and Dujardiii ; but the first 

 full account of their peculiar organisation was given by Stein in his Organismus dcr 

 I/ifitsionsthierchen. Misled, however, by their parasitic habits, Stein originally sub- 

 posed them not to be independent types, but to be merely transitional stages in the 

 development of Vorticellince and other ciliate Infusoria; this doctrine he long 

 since abandoned. Much information as to this group will also be found in the 

 beautiful Etudes sitr les Infusoires et Ics Bliizopodes of MM. Claparede and Lach- 

 mann, Geneva, 1858-61. 



