REPRODUCTION 243 



ball of protoplasm as in Gregarina longa; a spade-shaped structure 

 as in Pileocephalus hern'; a long knobbed proboscis either simple or 

 provided with spines as in Stylorhynchus longicollis or Gmiorhynchus 

 monnieri; or there may be many finger-form processes as in Echino- 

 mera hispida or thread-like processes as in Pterocephalus giardi. 

 In Corycella armata it becomes a single crown of hooks; in Beloides 

 firmus hooks combined with a lone spine. While these epimerites 

 serve primary for attachment, they also serve, in some cases at 

 least, as food-getting organs. In Pyxinia moebiuszi the epimerite 

 forms a long haustoria-like process which extends through the 

 epithelial cell of the gut and into the blood lacunae of the sub- 

 mucosa (Fig. 103, p. 201) and in Stylorhynchus longicollis a canal 

 is said to extend from the tip of the epimerite through the proto- 

 merite and into the deutomerite of the parasite serving for the 

 passage of food (Leger). 



The buds of Suctoria have a rather complicated developmental 

 history, especially in forms whose "embryos" are parasitic in other 

 Protozoa (Sphaerophrya species). The buds possess cilia which are 

 arranged in different patterns in the various species, and by which 

 they swim actively about until they finally settle down for develop- 

 ment. They also possess, as a rule, some longer cilia at the anterior 

 end which have been homologized with the adoral zone of the ciliated 

 Infusoria, and at the posterior end they possess a sucking disc by 

 means of which the buds attach themselves to some solid object 

 either living or lifeless, and from which a stalk is developed. With 

 growth of the stalk the cilia are absorbed and tentacles— suctorial, 

 piercing or seizing— are developed. In the parasitic forms the cili- 

 ated embryos may develop tentacles while in the motile condition, 

 but on coming in contact with a quondam host, cilia and tentacles 

 are absorbed and as an ectoparasite the young form makes a pit 

 in the cortex of the host. It may then reproduce by cell division 

 in this pit until as many as 50 or more are produced, and these 

 escape through a slit-like birth opening of the improvised brood 

 pouch. 



In some types of Protozoa finally, especially in the colonial 

 flagellated forms, the single cell undergoes a series of cleavage 

 stages the sequence of which is similar to that of many types of eggs 

 of Metazoa. This is particulary striking in forms like Epistylis, 

 Zoothamnium and other colonial filiates, which, as adults, consist 

 of more or less definite numbers of cells arranged in definite patterns. 



