THE PARASITE MINCHINIA. 453 



especially good for this purpose, and when followed by Ehdich's 

 htematoxylm enables the spore nucleus to be well stained. 

 Prolonged immersion in distilled water had no apparent effect on 

 the spore. Iodine stained the chitinous coat yellow but otherwise 

 had no result. Adult spores were occasionally induced to open 

 by pressure and reagents combined (PI. II. fig. 16). The oper- 

 culum always opened away from the tail and turned inside out, 

 but remained attached by the outer membrane, which acted as 

 a hinge. 



Appai'ently the spores of Minchliua are set free only by the 

 death of the host. 



From the structure of the spore one would expect it to be 

 destined for a prolonged free existence in sea-water. It has been 

 proved experimentally that the spores can remain for months 

 apparently unchanged in water, and can also undergo drying to 

 some extent. No success, however, has been obtained in attempts 

 to make them infect other Chiton directly. Living spores have 

 resisted all attempts to make them open. On some occasions 

 spores have been introduced into the oesophagus of a Chiton by 

 means of a very fine pipette ; on another occasion a few spoi'es in 

 a tiny piece of blotting paper tied with a fine silk thread were 

 introduced into the oesophagus of an uninfected Chiton, but on 

 removal after several hours were found to be quite unchanged. 

 At other times spores, after being in sea-water, have been mounted 

 with teased portions from different regions of the alimentary 

 canal, all with no result. One such preparation sealed up on 

 November 27th, and another on December 18th, lost all bacterial 

 infection after a few days, and were on March 22nd quite stei'ile 

 with the spores unchanged. 



Uninfected specimens of Chiton were also kept during March 

 and April under conditions as normal as possible except for the 

 presence of numerous spores of Mmchinia in the water. Although 

 the Chiton ate the fucus to which spores easily adhei-e, they did 

 not become infected duiing seven weeks nor were any spores 

 found in their alimentary canals *. 



Attempts were then made to infect othei- animals from the rocks 

 at the same zone with the spores of Umchinia, as it was thought 

 that possibly shore fish, etc. might become infected in this way 

 with another vegetative stage of Mmchinia. Owing to the courtesy 

 of the Director, these experiments have been carried on in the 

 Marine Biological Laboratory, Plymouth, and I am indebted to 

 Mr. A. J. Smith for much valuable assistance. In each case stones 

 with seveial Chiton attached Avere introduced into ]a)-ge tanks 

 through which water was cii'culating and containing the animals 

 being experimented upon. The results of these experiments were 

 as follows : — 



1. Bleriny. — These fish attacked the Chiton readily. All stages 



* Sec note at ctuI of paper. 



