162 



THE SPOROZOA 



totally erroneous, have remained uncontraclicted for ten years, during 

 which time they have got into numerous text -books and have been 

 generally accepted and taught. 



The spores of Monocystis do not appear to be able to develop 

 further in the earthworm, but require to be transferred to a 

 fresh host before they can germinate. How the infection is 

 effected has not yet been ascertained in the case of the type 



FIG. 8. 



Ripe cyst of Monocystis, showing the numerous spores (pseudonavicellae) scattered within 

 the cyst, without any cystal residuum present. (From Lankester.) 



that has been selected for description, and the course of events 

 can only be conjectured by analogy from what is known to 

 take place in other Sporozoa. It is highly probable that the 

 spores pass to the exterior and are scattered broadcast in the 

 earth, and that they are then swallowed accidentally by an earth- 

 worm with its food, and so pass into its digestive tract. The 

 action of the digestive juices upon the spores has the effect of 

 causing the sporocysts to burst open, setting free the sporozoites, 

 which are actively motile and possess the power of boring their 

 way through cells and tissues. In this way the sporozoites prob- 

 ably traverse the wall of the earthworm's intestine and reach the 

 reproductive organs, where each one attacks a sperm-mother-cell 



