PROTOZOA AND OTHER ANIMALS 959 



the young trophonts grow in the fluid contained in the discarded exo- 

 skeleton. The proteins accumulate in a violet trophic mass, giving the 

 color (which in other genera may be orange, red, and so forth) so 

 characteristic of ciliates of the family Foettingeriidae. Unlike many» 

 apostomes, the trophont does not become encysted. Linear palintomy 

 occurs in the motile stage, producing from eight to sixty-four daughter 

 tomonts, which metamorphose into tomites. In addition to the natural 

 host, the tomites will become fixed on the gills of Portunus holsatus, on 

 which development proceeds normally. 



In a third group of apostomes, in which there is only the genus 

 Synophrya, the trophont is at one stage parasitic in the tissues of the 

 crustacean to which the phoront is attached. Synophrya hypertrophica 

 (Fig. 205) is phoretic on Portunus depuratus, and also on other species 

 of Portunus and Carcinus niaenas. The sanguicolous trophonts are in- 

 ternal parasites in the branchial sinus of Portunus or the subcutaneous 

 sinus of Carcinus. They are large, mouthless, immobile, irregularly lobed 

 masses under the integument, enclosed in a double envelope. The re- 

 sulting lesions of Carcinus appears as brown or black spots 1-4 mm. in 

 diameter, found chiefly on the dorsal surface of the carapace. They oc- 

 cur in a high percentage of crabs less than two centimeters in diameter, 

 but not on large crabs. At ecdysis, tomites are produced which disperse 

 in the molted exoskeleton and develop into exuvicolous trophonts. When 

 growth is completed, these encyst as tomonts, each of which produces a 

 number of tomites. The tomites fix themselves and become phoretic 

 cysts on the integument of the gills or branchial cavity of the crab. The 

 parasites then migrate from the cyst into the underlying tissue. 



A fourth type of cycle is that of Foettingeria actiniarum, which is 

 heteroxenous. It was first known as an inquiline in the gastrovascular 

 cavity of sea anemones, some species of which are almost always in- 

 fected. It has been found in various sea anemones on the coast of France, 

 but it was not found in three species at Woods Hole. Chatton and 

 Lwoff (1935, p. 313) listed ten host species. The ciliates are chymo- 

 trophic. They enter the digestive mass when the coelenterate feeds and 

 there find their sustenance. The ciliates eventually leave the host and 

 encyst, the tomont undergoes palintomy, and the tomites become fixed 

 to a crustacean. The host-specificity of the phoronts is almost nil; the 



