314 RESEARCH IN PROTOZOOLOGY 



The stained smears should next be studied. Make a large num- 

 ber of drawings, showing the front, side and end views of mature 

 spores, and also developmental stages which will be more clearly 

 noticed in this condition than in the fresh state. Measure the spores. 

 Cepede (1906) first called attention to the fact that fresh spores 

 and fixed, stained and mounted spores differ in size and justly 

 insisted that for taxonomic purposes measurements of the spore 

 should be accompanied by a statement of the condition — whether 

 fresh or fixed — in which the spores were measured. For Myxoh- 

 olus cycloides, Cepede gave the following dimensions : fresh 

 spores: length 13. 5- 16//; breadth 11-13//; mounted spores (Schau- 

 dinn, Heidenhain, balsam) : length 10.5-12/1; breadth 7.5-8/f. Thus 

 the length and breadth of the spore decreased by twenty-five and 

 thirty-five per cent, respectively, by fixation and mounting. The 

 writer also pointed out the importance of the matter (Kudo, 

 1921a) and showed that in the case of Lcptotheca ohlmacheri 

 the decrease in dimensions of fixed spores was due to shrinking 

 of the entire spore. Various fixatives and staining methods were 

 used for both smears and sections. The sutural diameter, breadth 

 and thickness of fixed spores were approximately 16, 28 to 29 and 

 17 to 21%, respectively, smaller than those of fresh spores. For 

 this reason, one must use care in comparing the dimensions of 

 spores under observation with those of previously known species 

 which have been observed under various circumstances. 



Frequently one has to study a specimen which has already been 

 preserved in alcohol or formol, the most commonly employed pre- 

 servatives. A part of the cyst or the organ of the host fish, is 

 removed on a slide and washed in distilled water. A number of 

 improved hanging drop preparations should be made from it and 

 studied in a way similar to that which was described for fresh 

 material. 



Extrusion of the polar filaments from preserved . spores does 

 not ordinarily take place with the methods effective for fresh 

 spores. Gurley (1894), however, stated that in alcoholic speci- 

 mens, spores occasionally extruded their polar filaments under the 

 action of sulphuric acid or iodine. Almost all of the freshly pre- 

 served spores may extrude their polar filaments. Kudo (1920) 

 fixed the gills of Carpiodcs difforinis which carried a number of 

 cysts of Myxoholus discrcpans in Carnoy's alcohol-acetic for twen- 

 ty-four hours and preserved them in ninety-five per cent alcohol. 



