1914.] NATURAL SCIENCES OF PHILADELPHIA. ' 217 



it stands out very clearly when the spores are viewed with rather 

 low powers, it seems for the most part to be no more than a clear 

 space in the cytoplasm, and it is only occasionally that a definitive 

 nuclear membrane can be demonstrated. Within it is normally 

 provided with a number of chromatin granules. These granules 

 vary a good deal in size. At times they are quite minute and occur 

 in clusters and chains. More frequently, however, they are quite 

 large, round, or elongated, and appear to be wholly free in the nuclear 

 sap. At times, also, there is a more or less typical ch/j.natin net. 

 Whereas these differences may have some significance, it is perhaps 

 best to regard them merely as variants of some fundamental plan. 



The spores of certain species of the Sarcosporidia which attack 

 mammals are described and figured as being liberally provided with 

 rather densely staining granules, concerning which there has been a 

 good deal of theoretical discussion. Frequently, also, such spores 

 have been described as showing a differentiated area at one end, and 

 attempts have been made to correlate this area with the polar cap- 

 sules of the spores of the Myxosporidia. In the case in hand, the 

 spores of Sarcocystis leporum, there is at least no question about the 

 structure, which is remarkably clear cut and perfectly obvious. 

 And the rostrum of this spore, whatever may be its homologies, is 

 clearly the analogue of the rostra of the sporozoites and merozoites 

 of Coccidia. Moreover, it seems an entirely safe assumption 

 that its function is to enable the spore to drill its way into the intes- 

 tinal epithelium of its host, without prejudice as to whether this 

 host be an invertebrate, another rabbit, or some carnivorous mammal 

 or bird which preys upon the rabbit. 

 Sarcocystis setophagae sp. n. 



Stiles (1895 c)^ notes that Dr. Hassall, of the Bureau of Animal 

 Industry, discovered a sarcosporidian in the muscles of a redstart 

 {Setophaga ruticilla), and a description of this parasite was promised 

 at the time. This description, however, was never published, and the 

 material, consisting of two cysts embedded in paraffin, was recently 

 given to me by Dr. Hassall. 



Based upon the number of sections yielded by the cysts, their 

 length was about 2.5 mm., while the largest cross sections measured 

 about 1 mm. in diameter. Hence the cysts are thick in proportion 

 to their length, which seems characteristic for Sarcosporidia of birds. 

 The cysts were divided into the usual compartments. 



1 Stiles. 1895 c. — New American finds of Sarcosporidia (Notes on parasites. 

 28.) Vet. Mag., Phila., v. 1 (11) (Nov., 1894), Jan. 17, pp. 728, 729. 



