1903.] NATURAL SCIENCES OF PHILADELPHIA. 641 



31. Gregarina diceli^ Crawley. 



32. Gregarina xylopini Crawley. 



33. Gregarina boletophagi Crawley. 



III. 



The time required for a gregarine cyst to mature appears to vary to 



a very remarkable degree. I have information on seven species, as 

 follows : 



No. of days. Month. 



Gregarina achet^abbreviat.^i; 1 August. 



GiGADucTus parvus 2-3 August. 



Gregarina calverti 4 August. 



Cnemidospora spiroboli 8 May. 



ACTIXOCEPHALUS HARPALI 9 AugUSt. 



ACUTISPORA MACROCEPHALA 10 May. 



AcTiNocEPHALus DUJARDiNi 30 April-May. 



Although the number of cases is quite small, they point to one or 

 two facts of general interest. The first three species mentioned, in 

 which the period varies from one to four days, are all animals of which 

 the cysts open by means of sporoducts. This suggests the conclusion 

 that when sporoducts are developed the maturation period is short- 

 ened, although wherein the signification of this apparent correlation 

 may lie is decidedly problematical. 



The most striking case is that of Gregarina achetceabhreviahe. These 

 cysts had not passed to the exterior in the usual way, but were obtained 

 from the intestinal contents of a slaughtered cricket. They then 

 showed the yellowish disks indicative of the approaching eversion of 

 the sporoducts (see p. 639), and in consideration of the short time 

 which elapses from the appearance of these disks to eversion, it is not 

 unlikely that the process may take place in the host intestine. There 

 is no inherent unlikelihood in such an event, although it would prob- 

 ably not lead to auto-infection. The spores, released in the fecal 

 masses of the posterior portion of the cricket gut, would merely pass 

 to the exterior free instead of enclosed within a cyst, there to await 

 their destiny. 



In the case of Gigaductus parvus the cysts were also removed from 

 the host intestine, which gives this species a very short period. The 

 cysts of Gregarina calverti were obtained from the feces of the host, 

 and hence the four days represents the time required after the cyst has 



^ Incorrectly given as discccli in the original description. 

 41 



