126 R. KUDO. 



THE RELATION BETWEEN THE PARASITE AND THE HOST. 



I have remarked about this subject before (Kudo, '21, '22) and 

 do not at present have any additional statement to add. So far 

 I have failed to observe adult mosquitoes infected by the proto- 

 zoon. But from what I have recently seen in the cases of infection 

 of adult anopheline mosquitoes by Thelohania legeri and Nosema 

 anophelis in Georgia, it is quite possible that the Culex larvae 

 lightly or moderately infected by Stempellia magna would be able 

 to metamorphose into adults; on the other hand, when the 

 infection of the host larvae by the microsporidian is to such an 

 extent as to show a typical symptom to unaided eyes, the host 

 larva would die before completion of larval life. 



SUMMARY. 



1. Stempellia (Thelohania} magna was found to be parasitic in 

 the larvae of Culex pipiens (Illinois, 1919) and of C. territans 

 (Pennsylvania, 1920). 



2. The infection experiment shows that the larva? become 

 infected by feeding upon the infected larval tissue. 



3. The emergence of the sporoplasm of the spore taken into the 

 gut lumen of a new host takes place in the posterior part of the 

 mid-gut from 6 to 40 hours after feeding on the infected material. 



4. The schizonts are first noticed in the adipose tissue of the 

 mid-gut and of adjacent tracheae. 



5. The sporogony did not start in the larvae examined four 

 days after feeding on the infected material. 



6. Schizogony is a binary fission of various types. The final 

 form is binucleated. The two nuclei undergo autogamy, forming 

 a sporont. 



7. The sporont develops into ordinarily two, frequently one or 

 four and rarely eight sporoblasts; these develop into two, one, 

 four and eight spores. 



PAPERS CITED. 

 Debaisieux, P. 



'19 Microsporidies parasites dea larves de Simulium. Thelohania varians. 



La Cellule, 30, 47-79. 

 Kudo, R. 



'16 Contributions to the Study of Parasitic Protozoa. I. On the Structure 



and Life-history of Nosema bombycis Niigeli. Bull. Impcr. Sericult. 



Exp. Stat., I, 31-51. 



