247] STUDIES ON GREGARINES —WATSON Z7 



one has been seen to complete itself. This is accounted for probably by 

 the fact that pressure is exerted on most of the incipient ducts by the 

 slide and cover slip, and growth to completion thus inhibited. One duct 

 is often directed horizontally between the two surfaces and it always is 

 this lateral duct which develops and through which spores are extruded. 

 When there is considerable debris in the vicinity of the developing cysts, 

 the ducts are often coiled and twisted about the cyst itself. I have never 

 been able to incite spore exudation without the use of a cover slip for even 

 in a carefully sealed damp chamber there is enough volume within the 

 chamber to cause sufficient evaporation to dry up the unprotected cyst. 



The duct which is formed is very long, 25 mm. or eight times the ra- 

 dius of the cyst (Fig. 249). The ducts grow inward from the periphery 

 where they first appear to the region of the residual mass of protoplasm. 

 Then they grow outward from the periphery until they acquire the enor- 

 mous length attained in a few species. The growth outward is from the 

 region of the periphery, the older portion being pushed ahead. The tip 

 of the long duct is orange colored as is the disc from which growth be- 

 gan, showing that the oil globules are pushed along with the first out- 

 pushing of the tube. There does not seem to be an eversion of the duct 

 here, as in Gregarina rigida and other species (Lankester, 1903:183). 



The spores emerge in chains which soon break up into small seg- 

 ments. These spores (Fig. 255) are barrel-shaped and truncate at the 

 ends. They possess an epispore and endospore easily discernible w^hen a 

 stain is used on the slide. They are slightly cupped at the ends. I thinlj 

 there is a corona of very delicate spines or cilia at each end which servea 

 to hold the spores together in chains and to furnish a means of locomo- 

 tion for the isolated spores. That spor-es do move from place to place is 

 easily determined by watching a few chains of freshly liberated spores 

 on a slide. (Care should be taken that the slide is undisturbed and not 

 allowed to evaporate). In a few hours no two spores will be left attached 

 but they will lie in small clusters or scattered over a whole field. 



Sometimes spore ducts do not develop and the cyst has superficially 

 undergone but little differentiation, yet upon crushing the walls after a 

 day or so when the spore ducts should have been formed, perfectly 

 formed spores emerge, to all appearances and staining reactions identi- 

 cal with those liberated in the usual way. Nothing could be said of their 

 potency as compared with those extruded normally. 



The content of the spores varies greatly. If the cyst is broken be- 

 fore the spore ducts have had a chance to form, and apparently before 

 tlie spores are ripe, they will be found to contain many small clustered or 

 isolated chromosomes which stain deeply. All the spores from a given 

 cyst are in approximately the same stage of development. Another 

 broken cyst will yield spores with fewer chromosomes, from ten to fif- 



