156 Mr. C. C. Dobell. Observations on the [Nov. 19, 



instantly fixed by immersion in hot sublimate-alcohol containing a trace of 

 acetic acid (Schaudinn). After fixation the films were treated with alcohol 

 containing iodine, and stained in Biitschli's modification of Delafield's 

 hsematoxylin.* This I prepare by adding 1-per-cent. acetic acid solution to 

 a 0*5-per-cent. solution of the ordinary concentrated Delafield's hsematoxylin 

 in water until a pink colour is produced. Staining, for all stages except 

 spores, is complete in from 15 to 30 hours. 



Griemsa's modification of the Komanowsky-Nocht stain was tried, among 

 others, but it proved to be of little use for delicate nuclear structures, owing 

 to the drying which necessarily takes place. 



Transverse sections of the gut were made, but they were found to be 

 unsatisfactory. Moist films are far more useful for examining the Coccidia. 



I will now proceed to describe the stages which I have observed and which 

 differ from those hitherto recorded. 



(1) Association. — The entire genus Adelea is characterised by a precocious 

 association of the gametocytes. This was observed in A. ovata as long ago 

 as 1875, although, strangely enough, it was not even suspected of being 

 connected with any sexual process. Association, it may be noted, takes 

 place in the lumen of the gut, and not in the epithelium. Siedlecki, who 

 ultimately interpreted this phase correctly, states that but a single micro- 

 gametocyte ever attaches itself to a macrogametocyte. Only once did he 

 observe two microgametocytes attached to the same female individual. My 

 observations, on the contrary, lead me to believe that this condition is not 

 uncommon. I have seen upwards of a dozen instances in which two micro- 

 gametocytes were attached to the same macrogametocyte. Apparently, 

 these microgametocytes do not always develop or become attached 

 simultaneously, for they may be found in different stages of maturity 

 (cf. Plate 3, fig. 3). Association in which more than one microgametocyte 

 takes part has been described by Laveranf in the closely allied form Klossia 

 helicina. 



An association of two microgametocytes with one another as described 

 in A. mesnili (Perez) and A. zonula (Moroff), has never come under my 

 observation. 



(2) Formation of Miceogametes. — The only detailed account of the 

 genesis of the male gametes of A. ovata is that given by Siedlecki. He 

 states that the nucleus of the microgametocyte divides into two daughter- 

 nuclei, each of which then divides in a plane at right angles to that of the 

 first division, so that four nuclei result. These nuclei then develop into the 



* Biitschli, 'Zeitschr. f. wiss. Mik., 5 ix, 2, 1892, p. 197. 

 t Laveran, 'C. E. Soc. Biol. Paris,' 1898 (Novembre). 



