16 ILLINOIS BIOLOGICAL MONOGRAPHS [226 



from under the flotsam and jetsam which is brought to the inside of the 

 spit by the incoming tide. There are no waves on this inner beach to 

 change appreciably the upper limits of the tidal zone and the crickets 

 were undisturbed. The cricket population is large and flourishing be- 

 cause of the influx of organic debris. Thus the insects are confined to a 

 restricted habitat and as cysts are produced and the spores scattered, the 

 animals are reinfected over and over again. 



A number of crickets were taken in August from debris along the 

 shores of Northport Harbor and Huntington Beach, Long Island, and all 

 were uninfected. Both these localities are part of the exposed shore of 

 Long Island Sound. A number were taken inland at Arlington, New Jer- 

 sey, and were also uninfected. Practically every cricket examined in the 

 late summer at Cold Spring Harbor and at Oyster Bay (four miles dis- 

 tant) was infected. The only explanation which can be offered by the 

 writer for these phenomena is that the spores, having once become estab- 

 lished in restricted area, have not yet found the means of becoming scat- 

 tered broadcast but reproduce themselves in enormous numbers in re- 

 stricted localities. 



RELATION OF PARASITE TO HOST TISSUE 



The effect of the parasite on the host is a subject still under discus- 

 sion. Very little actual investigation has been carried on in this field but 

 it is one which offers many interesting problems in biological chemistry. 



In the growing stages, the Eugregarine is either completely intercel- 

 lular without an epimerite, or possesses an epimerite by which it is at- 

 tached to the epitelial cells of the host intestine, this factor depending on 

 the family to which it belongs. All the Acephalinae (including Monocys- 

 tis) and some of the Cephalinae (e. g. the Stenophoridae and the genus 

 Frenzelina of the Gregarinidae ) are intercellular; most of the cephaline 

 Eugregarinae are not, however, intercellular but possess epimerites 

 which alone penetrate the host cells. 



When the parasite is completely intercellular, the sporozoite pene- 

 trates the free end of the cell, works its way inward by ameboid move- 

 ment (Leger and Duboscq, 1909) and comes to rest in the vicinity of the 

 nucleus. The parasite at once begins to affect the nucleus, causing the 

 breaking up and rearrangement of the chromatin into small more or less 

 spherical bodies which react differently to the stain than do the normal 

 nuclei. The cytoplasm also is affected chemically for it stains less deeply 

 than the normal cell cytoplasm. 



Siedlecki (1901) thinks these changes are due to a substance secreted 

 by the parasite. Using Monocystis ascidiae for material, he found that 

 the parasitized cell is at first greatly enlarged. The parasite within this 

 enlarged cell then increases enormously in size so that the host cell and its 



