102 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I4I 



wood is broken down into compounds the cockroach can utiHze by the 

 protozoa which elaborate a cellulase and possibly a cellobiase (Trager, 

 1932), Only molting nymphs of Cryptocercus can pass the protozoa 

 on to the newly hatched young, so that molting and hatching must 

 happen concurrently each year or the young die. 



The sexual cycles in species of protozoa in the genera Tricho- 

 nympha, Saccinohaculus, Oxymonas, Monocercomonoides, Hexamita, 

 Encomonympha, Leptospironympha, Urinynipha, Rhynchonympha, 

 Macrospironympha, and Barhulanympha (fig. 3, B) are induced by 

 hormones produced by Cryptocercus only during its molting period 

 (Cleveland, 1931, 1947, 1947a, 1949- 1956a). Perhaps the prothoracic 

 gland hormone of the host may be responsible for initiation of the 

 flagellate sexual cycles (Cleveland and Nutting, 1955). The protozoan 

 sexual cycles may be used as indicators of the onset of molting in 

 Cryptocercus; thus different species of protozoa begin their sexual 

 cycles from 35 days before to 2 days after molting of the cockroach 

 (Cleveland and Nutting, 1954). Hollande (1952) and Grasse (1952) 

 have reviewed the roles and the evolution of the flagellates in Crypto- 

 cercus and in termites. 



The protozoa of cockroaches and termites are clues to the relation- 

 ship between these two groups of insects. Kirby (1927) pointed out 

 similarities between Endamoeba hlattae of Periplaneta and the 

 amoebae of the termite Mirotermes, suggesting that these protozoans 

 were probably derived from an amoeba in an ancestor common to 

 both blattid and termite. Kirby (1932, in Kidder, 1937) found a 

 species of Nyctotherus in Amitermes that resembles Nyctotherus 

 ovalis from domestic cockroaches. The belief that the termites and 

 cockroaches had a common origin is also strengthened by the similari- 

 ties between the hypermastigotes of both Cryptocercus and termites 

 (Cleveland et al, 1934). 



The cockroaches Cryptocercus and Panesthia both feed on wood, 

 but the protozoa found in Panesthia resemble more closely the species 

 in domestic cockroaches than those in Cryptocercus. The Clevelan- 

 dellidae ( from Panesthia ) are closely related to Nyctotherus and have 

 probably evolved from common ancestors. However, the separation 

 of the Clevelandellidae from Nyctotherus must have taken place at a 

 later date than the divergence of their hosts, otherwise representatives 

 of that family would probably also be found in Periplaneta and Blatta 

 (Kidder, 1937). 



The protozoa of Cryptocercus can be transferred from one indi- 

 vidual to another (Nutting and Cleveland, 1954). They can also be 



