REPRODUCTION OF INFUSORIA 



785 



<listinct generic form, Megatricha, And, according to the observa- 

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

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

 filamentous Alga? 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 amcebiform shapes (fig. 

 599, l, 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 Podophrya 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 Podophrya quadripartita. 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 Avay prepara- 

 tory to propagation, has not yet been ascertained. 2 



1 Jouni. 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 Oi-guttismus der 

 Infustoiistliierclien. Misled, however, by their parasitic habits, Stein originally sub- 

 ] >osed them not to be independent types, but to be merely transitional stages in the 

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

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

 beautiful Etudes sin- les Infmoires et les Rhizopodes of MM. Claparede and Ltich- 

 maun, Geneva, 1858-01. 



3 



