26 



IN VERTEBHA TE MORPHOLOO T. 



tlie pseudofilaria, and this, gradually losing its motility, de- 

 velops into the adult form. 



Pig. 13. — Rbpboduction of Gebgabine (from Hertwig). 



1. Glepsidrina blattarum in conjugation; ck = ectosarc, en = endosarc.cK = 



cuticula, pm = anterior portion, dm = posterior portion, n = nucleus. 



2. Cysts in transformation into . pseudonavicellae; pra = pseudonavioelloe; 



rk = residual protoplasm . 



3. A, a pseudonavicella strongly magnified; B, the same divided into spores, 



sk; n — nucleus, rk = residual protoplasm. 



2. Order Myxosporidia. 



The Myxosporidia are found almost exclusively parasitic 

 in Fishes, affecting principally the skin, but also occurring 

 in the internal organs, such as kidneys, spleen, and urinary 

 bladder. They consist of irregularly-shaped masses of pro- 

 toplasm, sometimes reaching a length 0.1 mm., but usually 

 falling considerably short of this size. 'Frequently they are 

 enclosed in cysts developed from the tissues of the host, but 



